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Electro-Etching

Workshop

John Fetvedt

www.bijoux-de-terre.com

http://www.bijoux-de-terre.com/

John Fetvedt www.bijoux-de-terre.com September 2, 2017 2

Table of Contents Electro-Etching .............................................................................................................................................. 5

Advantages of Electro-Etching .................................................................................................................. 5

Safety First ................................................................................................................................................ 5

Basic Electricity ............................................................................................................................................. 6

Definitions ................................................................................................................................................. 6

Electro-Etching 101 ....................................................................................................................................... 7

Introduction .............................................................................................................................................. 7

Basic Setup for Electro-Etching ................................................................................................................. 7

Measuring Volts ........................................................................................................................................ 7

Measuring Amperes .................................................................................................................................. 8

Volts vs Amps ............................................................................................................................................ 8

Current Density ......................................................................................................................................... 9

Cross Section of a Typical Electro-Etching ................................................................................................ 9

Etching the Design (intaglio etch) vs Etching the Background (relief etch) .............................................. 9

Increasing the Current Density ............................................................................................................... 10

Small Semi-Enclosed areas ...................................................................................................................... 10

Choice of Electrolytes ............................................................................................................................. 10

Resists ......................................................................................................................................................... 11

Computer Generated Resist Mask Options ............................................................................................ 11

Vinyl .................................................................................................................................................... 11

Laser Toner .......................................................................................................................................... 12

Photosensitive Dry Film ...................................................................................................................... 16

Other Resist Options ............................................................................................................................... 19

Contact Paper ...................................................................................................................................... 19

Tape ..................................................................................................................................................... 19

Fingernail Polish .................................................................................................................................. 19

Paint Pens ............................................................................................................................................ 19

Electrolytes ................................................................................................................................................. 20

Cupric Nitrate (Cu(NO3)2) ........................................................................................................................ 20

Preparing the Cupric Nitrate Solution ................................................................................................. 21

Disposing of the Cupric Nitrate Solution............................................................................................. 22


Sodium Chloride (NaCl) ........................................................................................................................... 22

Preparing the Sodium Chloride Solution ............................................................................................. 22

Disposing of the Sodium Chloride Solution ........................................................................................ 22

Copper Sulfate (CuSO4) ........................................................................................................................... 23

Preparing the Copper Sulfate Solution ............................................................................................... 23

Disposing of the Copper Sulfate Solution ........................................................................................... 23

Silver Nitrate (AgNO3) ............................................................................................................................. 23

Preparing the Silver Nitrate Solution .................................................................................................. 23

Disposing of the Silver Nitrate Solution .............................................................................................. 24

Sodium Nitrate (NaNO3) .......................................................................................................................... 24

Preparing the Sodium Nitrate Solution ............................................................................................... 24

Disposing of the Sodium Nitrate Solution ........................................................................................... 24

Power Source Options ................................................................................................................................ 24

Rectifiers ................................................................................................................................................. 25

Other Power Supply Options .................................................................................................................. 25

Batteries .............................................................................................................................................. 25

Power Supplies .................................................................................................................................... 26

Homemade Power Supplies ................................................................................................................ 27

Automotive Battery Chargers ............................................................................................................. 27

Metals ......................................................................................................................................................... 28

Copper ..................................................................................................................................................... 28

Silver ........................................................................................................................................................ 28

Aluminum ................................................................................................................................................ 28

Nickle Silver (a.k.a. German Silver) ......................................................................................................... 29

Red Brass (a.k.a. Jeweler’s Brass, NuGold, Jeweler’s Bronze, or Merlin’s Gold) .................................... 29

Bronze ..................................................................................................................................................... 29

Steel ........................................................................................................................................................ 29

Preparing the Package for Etching .............................................................................................................. 29

Etching the Background (relief etch) vs Etching the Design (intaglio etch) ............................................ 29

Relief Etching with All Resists ............................................................................................................. 30

Intaglio Etching with Vinyl Resist ........................................................................................................ 31

Intaglio Etching with Photosensitive Dry Film or Toner Resist ........................................................... 32


Q-Tip Etching ............................................................................................................................................... 33

Etching from Photographs .......................................................................................................................... 34

Colorscape App ....................................................................................................................................... 34

Background Removal using Microsoft Powerpoint ................................................................................ 35

Vacuum Filtering the Electrolyte ................................................................................................................ 36

Burnishing with a Tumbler .......................................................................................................................... 37

Coating Base Metal Jewelry ........................................................................................................................ 38

Electro-Etching Studio Equipment .............................................................................................................. 38

MSDS for Common Etching Chemicals and Resulting Products ................................................................. 41

Thank you for attending my workshop. ...................................................................................................... 42


Electro-Etching Electro-Etching, also called galvanic-etching, is described by Wikipedia, the free encyclopedia, as “a metal etching process that involves the use of a solution of an electrolyte, an anode and a cathode. The metal piece to be etched is connected to the positive pole of a source of direct electric current and is called the anode. A piece of the same metal is connected to the negative pole of the direct current source and is called the cathode. In order to reduce unwanted electro-chemical effects, the anode and the cathode should be of the same metal. Similarly the cation (the ion with a positive charge) of the electrolyte should be of the same metal as well. When the current source is turned on, the metal of the anode is dissolved and converted into the same cation as in the electrolyte and at the same time an equal amount of the cation in the electrolyte is converted into metal and deposited on the cathode. Depending on the voltage used and the concentration of the electrolyte, other, more complex electrochemical effects can take place at the anode and the cathode but the solution at the anode and deposition at the cathode are the main effects.”

Advantages of Electro-Etching

• The chemicals used for electro-etching are not corrosive like the acids used for many other

types of etching. However, most of them are not good for the environment, particularly after

etching, and they need to be disposed of properly.

• Several of the electrolyte solutions commonly used for electro-etching rarely need to be

disposed of. They last for years as they do not become exhausted, and they do not need to be

periodically refreshed.

• Undercutting, or eating back under the resist, is generally far less with electro-etching than with

acid etching.

• No dangerous gasses, or fumes, are created during most electro-etching processes.

• When the same concentration of electrolyte, the same current, and the same time is used, an

etching is repeatable.

• When silver is etched using cupric nitrate as the electrolyte, the silver removed from the anode

can easily be recovered from the solution.

Safety First Safety glasses or face shield – Always wear safety glasses, or a face shield, when working near any of the

chemicals, both liquids and solids. If any of the solutions are accidently splashed into the eyes, use an

eye wash station to thoroughly wash the eyes with water.

Rubber gloves – Always wear rubber gloves when working near any of the chemicals, both liquids and

solids. If you are accidently splashed with any of the solutions, wash the area thoroughly with water.

Respirator – Always wear a respirator when working near any of the dry, solid chemicals.

Disposal of electrolytes – All solutions from the etching process may require special care when disposing

of them. Read the directions for proper disposing of each chemical. Do not just pour anything down the

drain.

Label chemicals and solutions – Store all chemicals and solutions is plastic bottles with plastic caps,

clearly labeled, and in a safe place away from children.


Read the Material Safety Data Sheets (MSDS) – Read the MSDS for all chemicals that you will be working

with, and for all the compounds that may be created during the etching process. MSDS are available on

the web at www.sciencelab.com, enter the chemical name in the “Search for Products” box on the

upper right side of the screen and look for a link to the MSDS.

Basic Electricity Don’t panic, there will not be a test on this subject. I just want to familiarize you with some of the terms

we may mention during the workshop.

Definitions A or amp (ampere) – An amp is the measurement of the amount of current that is flowing. Think about

an ampere as a measurement of the amount of water that is coming out of the faucet at any one time.

Ah (ampere hour) – An ampere hour is used to define the capacity of a battery. For example, a battery

rated as 1Ah can deliver 1 ampere of current for 1 hour. Look at an ampere hour as a measurement of

the total amount of water that is in the tank connected to a faucet.

Anode – The anode is the electrode that is attached to the positive (+) side of the power supply, usually

by a red wire. The anode is the metal that is to be etched.

Cathode – The cathode is the electrode that is attached to the negative (-) side of the power supply,

usually by a black wire. The cathode is NOT the metal that is to be etched.

Circuit – A circuit is a complete path through which an electric current can flow.

mA (milliamp) – A milliamp is equal to one one-thousandth of an ampere, i.e. 1 ampere equals 1000

milliamps.

Multimeter – A multimeter is an instrument designed to measure electric current, voltage, and usually

resistance, typically over several ranges of value.

Ohm – An ohm is a measurement of electrical resistance.

Ohms Law – Ohm's Law describes the mathematical relationship between electric current (ampere),

resistance (ohms), and voltage (volts). It is stated as volts = amperes * ohms, or amperes = volts / ohms,

or ohms = volts / amperes.

Resistance – The resistance is a measurement of the difficulty encountered by the current flowing

through an electrical circuit. Think of it as a nozzle on a hose that can be used to reduce the amount of

water coming out of the faucet. In the electro-etching setup, the resistance is caused by the electrolyte.

V (volt) – A volt is a unit of electromotive force. Think of it as a measurement of the pressure of the

water coming out of the faucet.

http://www.sciencelab.com/


Electro-Etching 101

Introduction I want to point out that I generally work on one or two small, 2 to 4 inch projects of silver, copper or

copper alloy at a time, and use minimum sized tanks. If you are going to work with other metals, on

large projects, or in a production mode, I suggest you research the literature and experiment on a small

scale until you understand the principles, hazards, and what might need to be altered, to scale up to a

larger production sized setup.

Basic Setup for Electro-Etching Prepare the electrolyte and place it in the etching tank. Connect one end of a red wire to the positive

(+) connection at the power source and the other end of the red wire to the anode, i.e. the metal piece

to be etched. Connect one end of a black wire to the negative (-) connection at the power supply and

the other end of the black wire to the cathode, i.e. a piece of scrap copper, and Bob’s your uncle.

Remember, all exposed metal that touches the electrolyte on the anode side of the etching tank will be

etched. This applies to the wire, or the alligator clip used to attach the metal blank to be etched, to the

positive lead from the power source. The electrolyte doesn’t know what it is supposed to etch and what

it is not supposed to etch. Cover all metal attached to the anode that may come in contact with the

electrolyte with a resist.

Measuring Volts Volts are measured using a multimeter with the selector switch set to read DC Volts. Connect the

alligator clip on the black wire from the multimeter to the cathode, and the alligator clip on the red wire

from the multimeter to the anode. The voltage can now be read on the display on the multimeter.


Measuring Amperes Amperes are measured using a multimeter with the selector switch set to read DC Amps. Disconnect

the red wire from the power supply at the anode and connect it to the red wire connected to the

multimeter. Connect the black wire from the multimeter to the anode. The amps can now be read on

the display on the multimeter.

Volts vs Amps When dealing with electro-etching, the measurement of interest is the amount of current measured in

amperes. The voltage really doesn’t matter all that much, except that by Ohm’s law, amps is equal to

volts divided by ohms. So, assuming that the resistance of the electrolyte doesn’t change, increasing the

voltage will also increase the current. Note however, that increasing the voltage too high may cause

undesirable side effects.

We are talking about the actual measured voltage and amps. The volts and amps listed on a battery, or

a power supply, indicate what the power supply can deliver under ideal circumstances, which may

different than what it is actually delivering under load. For example, a power supply listed as 5V 1.2A


was measured at 3.6V 0.69A during an etching procedure. The voltage and current displayed on a

rectifier during an etching operation show the actual values.

Current Density Current density is the measurement of the current (amperes) passing through a given area in a given

amount of time. For electro-etching, the area is the actual size of the area to be etched. It may be

difficult to use actual numbers because the area to be etched is usually complex and attempting to

figure out the actual size could be very involved.

The amount of material removed during the etching process is related to the current density and the

length of time the current is flowing. This allows us to make several statements about related etchings.

Increasing the current reduces the time required for a given area to be etched to a similar depth. For

example, if the current is doubled, the time for a similar etching depth will be halved, or if the current is

halved then the time required for a similar etching depth must be doubled.

Increasing the size of the area to be etched requires that either the current or the time, or both, must be

increased for the larger area to be etched to a similar depth. For example, if the area to be etched is

doubled then either the current must be doubled or the time must be doubled to achieve a similar

depth of etch in the larger area.

Increasing the time while holding the current and area constant will result in a deeper etching. For

example, doubling the time, while holding the current and area constant will result in twice the depth of

the etching.

Cross Section of a Typical Electro-Etching Ideally the cross section of an electro-etch would look like figure A on the right. However, the cross section of a typical electro-etch is somewhere in between figure A and figure B. Decreasing the current density will move the cross section up towards figure A, and increasing the current density will move the cross section down towards figure B.

Note that the depth of the etching is greatest along the edge of the resist and again at the edge of the

metal blank.

Etching the Design (intaglio etch) vs Etching the Background (relief etch) Typically a design will be much smaller in area than the area of the background (negative space)

surrounding the design. This means that designs can usually be etched faster, and at a lower current,

than background etches.


Increasing the Current Density Increasing the current density will result in a faster etch, but may also result in a rougher etching. The

right side of the photo below was etched at two times the current density, and in half the time, as the

left side. The depth of etching is about the same in both samples, but obviously the sample on the left,

which was etched with the lower current density, is a much smoother etching.

Small Semi-Enclosed areas Areas where the resist comes together to form small semi-enclosed areas, similar to the head of a

valley, will also be subject to the deeper etching with increased current density. This can be seen in the

following photo. The disk on the right side of the photo below was etched at about twice the current

density, and in about half the time, as the disk on the left. The depth of the etching in the center of the

snowflake is about the same on both disks. However, notice that the points of the snowflake on the

right are etched deeper and rougher than those on the left. In fact, the center point at the top of the

picture on the right disk actually etched all the way through the metal.

Choice of Electrolytes Electrolytes differ in the way they respond to the current density. The photo below shows the

difference in the quality of the etching when using cupric nitrate vs sodium chloride as the electrolyte.

Both samples were etched at approximately the same current density for the same length of time. The

left side of the picture was etched in cupric nitrate and the right side in sodium chloride. Both of the

samples have about the same depth of etching. But in order to achieve a smoother etching, the sample

etched in sodium chloride, on the right, should have been etched for a longer time at a lower current

density.


Resists A resist for electro-etching needs be only an electric insulator that will stay in place on the metal in the

electrolyte while the metal is being etched.

The careful application of the resist is the most critical step in the etching process. If the resist fails

the etching will not be successful.

Before applying the resist, I make sure the metal blank is flat, I scrub it lightly with Penny Brite to

remove any oxidation, and wipe it with denatured alcohol or acetone to remove any grease.

Computer Generated Resist Mask Options The most common options for computer generated resist masks for etching are:

• Vinyl masks, cut with a cutter, e.g. a Silhouette Cameo. Vinyl is good for designs that have large

areas that are not to be etched.

• Laser toner masks, printed with a laser printer or copier. Toner images are good for intricate

designs that do not have large areas that are not to be etched.

• Photosensitive Dry Film, even though it involves more steps to apply, is good for intricate

designs as well as designs that have large areas that are not to be etched.

Vinyl

One way vinyl resist masks can be prepared is by using the Silhouette Studio application and a Silhouette

Cameo cutter. There are many tutorials available on YouTube for Silhouette Studio and the Silhouette

Cameo cutter.

I have used Oracal 651 vinyl and Silhouette Matte vinyl with good results. However, this vinyl is opaque

and it can be a challenge to place the design in the correct location on the metal blank. I have also used

a transparent vinyl from Paper Street Plastics, available on Amazon, eBay, and other suppliers, with

good results. It is easier to place the design properly with transparent vinyl.

I have experienced seepage under the edges of the vinyl resist when using copper sulfate as the

electrolyte.


Tips for cutting vinyl resist masks using a Silhouette Cameo:

• I adjust a design, or a group of designs, to the upper edge, and try to fill up the row for the

entire width of the vinyl. This will reduce the amount of vinyl that is wasted.

• I go to the “Cut Settings” icon on the upper right of the screen and

o under “material type” click on “Vinyl”,

o click on “Editing: Vinyl” and set the cutting speed to 1 or 2 cm/s

• When cutting vinyl from a roll, I stay in the “Cut Settings” window and

o Click on “Advanced”,

▪ click on “Feed”

▪ set the “Additional Advance” option to 0.25”.

• When the cutting is completed, press “Advance to Crosscutter” on the Silhouette Cameo control

panel, and cut the design off on the back of the Silhouette Cameo using the cutter.

Applying the Vinyl Resist

1. Weed the parts of the design that are to be etched using a dental pick, needle, or sharp pointed tweezers.

2. Cut a length of Scotch MagicTM tape long enough to cover the design, place the tape on top of the design in the mask, and burnish the tape to the vinyl. It may take more than one strip of tape to cover the design. Overlap the strips of tape slightly.

3. Carefully peel the backing paper away from the vinyl exposing the sticky side of the vinyl.

4. Hold the mask so the sticky side is down, place the design on the metal blank, and press the vinyl down onto the metal. Burnish the vinyl to the metal.

Laser Toner

A laser printer, or copier that uses toner, must be used for this technology to work; ink jet printers will

not work. I have seen a large number of comments suggesting that Brother laser printers will not work

well, and a small number of comments suggesting that they can be made to work. Apparently some

Brother printers use a toner that has a higher melting point and the method of transferring the toner to

the metal blank must be modified to use a higher temperature.


The primary options for transfer media to print the mask on include Toner Transfer Paper, PnP Blue, and

PnP Wet. Be careful here, there are many things out there that call themselves toner transfer paper.

The Toner Transfer Paper I use is from PCB Fab-in-a-Box at www.pcbfx.com. I have also seen comments

suggesting that copier transparency film, glossy photo paper, and “slick” pages torn from magazines, can

be made to work. I do not have any personal experience using any of these substitutes. The difference

between Toner Transfer Paper (PCB Fab-in-a-Box) and PnP Wet vs PnP Blue and the other substitutes, is

that Toner Transfer Paper (PCB Fab-in-a-Box) and PnP Wet release the toner when soaked in water for a

minute or so, whereas with PnP Blue, and the other substitutes, it is a slight tug-of-war as to where the

toner will end up when the paper is pulled off of the metal blank.

When transferring the laser toner to the metal, the printed side of the transfer media will be towards

the metal blank. The design must be flipped horizontally, left to right, if it is not symmetrical, e.g. if it

includes letters or numbers, etc., before printing on the transfer media.

Inspect the transferred resist under magnification for pinholes before

starting the etching. The laser toner may not give 100% coverage to

larger areas of black, but the electrolyte will find the pinholes (photo

on right) and etch pits in areas that were not supposed to be etched.

Cover any pinholes in the resist mask using nail polish or paint pens.

Note: Some of the paint pens contain xylene and will dissolve laser

toner. Please refer to a later section on Paint Pens for information.

I have experienced some seepage under the edges of the toner when

using copper sulfate as the electrolyte.

Remove the laser toner following the etching by wiping the metal blank with a paper towel and acetone.

I use an HP Laser Jet P1102w printer in my studio to print my laser toner resist masks with good results.

I also make sure I use HP brand toner. I have seen comments that report that off brands of toner

replacement cartridges are sometimes less than satisfactory.

Transferring the Laser Toner from the Transfer Media to the Metal Blank

It is important that the laser toner be securely applied to the metal using both heat and pressure,

otherwise the resist may not fully adhere to the metal and will fail during the etching process. Make

sure the metal is very clean and free of oils by wiping it carefully with denatured alcohol or acetone.

I use the following technique to transfer the laser toner to the metal blank using a heat press as the heat

source.

http://www.pcbfx.com/


Starting at the bottom of the stack, because that is the way it actually gets stacked up:

• High temperature silicon pad – This is either the pad on the base of the heat press, or a silicon

pad if an iron or other heat source is being used. The pad helps to uniformly press the transfer

media against the metal with equal pressure, even if the metal is not perfectly flat.

• Paper – The clean sheet of paper protects the silicon pad from any excess toner transferring to

the pad. The paper should not have any printing on it, or the printing may transfer to either the

high temperature silicon pad or the metal at these temperatures.

• Transfer media – The side with the laser toner to be transferred is facing up

• Metal blank – The side of the metal to receive the design is facing down.

• Paper – The clean sheet of paper to protect the heat source from any excess toner. The paper

should not have any printing on it, or the printing may transfer to the plate of the heat press.

• Heat source – I use a heat press as the heat source. Most laser toners transfer well at about

275°-325°F.

Other reported methods of transferring the laser toner design to the metal blank include:

• Passing the transfer media and the metal blank through a laminator. This may require more

than one pass. Laminators that have the capability to adjust both the temperature and the

speed apparently work best.

• Placing the metal blank on a heat source, such as an electric griddle or an iron clamped upside

down in a vise, laying the transfer media on top of the metal blank with the design facing down,

and burnishing the toner onto the metal with a burnisher, a popsicle stick, or the back of a

spoon.

Transfer Media

There are at least three technologies specifically designed for transferring laser toner onto metal blanks,

Toner Transfer Paper (PCB Fab-in-a-Box), PnP Blue, and PnP Wet.

Toner Transfer Paper (PCB Fab-in-a-Box), PnP Blue, and PnP Wet are not cheap. If the design does not fill

an entire sheet consider cutting the media to the size needed and perhaps taping it to a sheet of plain

paper to carry it through the printer. In my studio, I cut the media into quarters of a sheet (5.5 x 4.25

inch rectangles) and feed it through the envelope feed slot in my printer.


Toner Transfer Paper (PCB Fab-in-a-Box)

Toner Transfer Paper from PCB Fab-in-a-Box is a special paper based product coated with the release

material that dissolves easily within a minute or two when placed in a pan of water.

To use Toner Transfer Paper (PCB Fab-in-a-Box), print or copy your design onto the shiny side of the

sheet using a laser printer or copier, and then apply it to the clean metal using heat and pressure.

Immerse the metal blank with the Toner Transfer Paper (PCB Fab-in-a-Box) stuck to it into a shallow pan

of water. After a minute or so the paper will release its hold on the toner and can be lifted off the metal

blank. Detailed information about the Toner Transfer Paper (PCB Fab-in-a-Box) process may be found at

www.pcbfx.com.

PCB Fab-in-a-Box also has a Green Toner Reactive Foil for sealing pinholes in the toner. It is applied to

the metal blank after the toner has been transferred to seal the toner. Personally, I have never had

much success with the Green Toner Reactive Foil.

PnP Blue

PnP Blue Transfer Film is an acetate sheet coated with a material that is designed to accept the laser

toner printing and release it onto the metal blank under the proper conditions.

To use PnP Blue, print or copy your design onto the dull side of the PnP Blue sheet using a laser printer

or copier, and then apply it to the clean metal using heat and pressure. There are a number of tutorials

available on YouTube that explain the process. Search for “PnP Blue etching”.

PnP Wet

(My source told me PnP Wet had been discontinued on 4/7/2017. However, I decided to leave the

information here until I can confirm that it is no longer being manufactured.)

PnP Wet is a special paper based product coated with the release material that dissolves easily within a

minute or two when placed in a pan of water.

To use PnP Wet, print or copy your design onto the shiny side of the PnP Wet sheet using a laser printer

or copier, and then apply it to the clean metal using heat and pressure. Immerse the metal blank with

the PnP Wet stuck to it into a shallow pan of water. After a minute or so the paper will release its hold

on the toner and can be lifted off the metal blank.

Other Transfer Media Options

There are also a number of other transfer media options that I have seen suggested on the forums. I

believe these other options are being used primarily to reduce expenses. Some of these options

include:

• Other Heat Toner Transfer Papers for DIY PCB – There are other sources for toner transfer

papers that are similar to PnP Blue. I have tried one other source, but the paper was so flimsy

that it had to be taped to another sheet of paper to get it through the printer successfully.

• Copier Transparency Film – Copier transparence film is a thin acetate sheet like PnP Blue, but

without the coating specifically designed to ease the release of the laser toner from the acetate.



I have experimented a couple of times using copier transparency film and have been

unsuccessful in getting an acceptable transfer.

• Glossy Photo Paper – Glossy photo paper is a coated paper backed product, but instead of

having a coating specifically designed to release the laser toner you are counting on whatever

coating is on the photo paper to release the laser toner. The paper must be soaked in water to

remove it from the metal blank, and my understanding is that it requires a much longer soaking

time and a light scrubbing. I have not tried using glossy photo paper.

• “Slick” pages torn from magazines – These are the very shiny pages found in some magazines,

and you are counting on the smoothness of the “slick” paper to release the laser toner. The

paper must be soaked in water to remove it from the metal blank, and my understanding is that

it requires a much longer soaking time and a light scrubbing. I have not tried using “slicks”.

Photosensitive Dry Film

Photosensitive dry film is a light sensitive film that is applied to the metal blank. A mask, printed on

transparency film is placed on top of the film, and the package is exposed to an ultraviolet (UV) light

source. The unexposed areas of the film are removed from the blank using a developer solution, and

the blank can then be etched. The film is sensitive and it is recommended that a yellow bug light be

used when working with it rather than normal room light.

A common problem is to treat the photosensitive dry film similar to photographic film. That is to say,

expose it to light until the desired density is reached and then develop it. This method leads to many of

the smaller traces being covered with “unexposed” resist that needs to be scrubbed out with varying

degrees of success. However, photosensitive dry film is a cat of a different color. It needs to have a

minimum exposure in UV light to define the pattern, be gently developed to remove the unexposed film,

and then exposed to UV light again finish the process. The key to determining the minimum required

exposure is to use an exposure guide such as the Stouffer 21 Step Sensitivity Guide T2115. Using the

minimum exposure time the unexposed film may be gently wiped off during the development process

leaving absolutely clean traces, and the second exposure to UV light completes the process.

I use a negative photo sensitive film, which means that the black areas of the mask are the areas of the

metal blank that will be etched. The photosensitive dry film comes in a roll, sandwiched between two

very thin protective films. Many of the sources for photosensitive dry film do not come with instructions

from the manufacturer. There are several videos on YouTube showing how people use it, but it is really

up to you to experiment and determine what works best for you.

I have experienced seepage under the edges of the photosensitive dry film resist when using copper

sulfate as the electrolyte. However, the seepage areas did not appear to be etched, but rather just

discolored, and I was able to polish them out.

I have worked with two different brands of photosensitive dry film, INSMA PCB Dry Film 38um

Photosensitive Film for Photosensitive PCB Circuit Production Photoresist Sheets and Puretch.


Applying the Photosensitive Dry Film

Remember, it is best to work with the photosensitive dry file under a yellow “bug” light from the time

you open the package until it has been developed.

The technique I use for photosensitive dry film is:

1. Print the design on a sheet of transparence film. The black portions of the mask are the areas to

be etched. – I use an inkjet printer because I feel it gives better coverage of the black areas. You

also need to use an inkjet transparency film to keep the mask from smearing. I flip the design

left to right before printing (see a later step as to why).

2. Clean and degrease the metal blank. – I do a light scrub with Penny Brite, rinse with water, dry,

and wipe with denatured alcohol or acetone.

3. Place the metal blank in a pan of water.

4. Cut a piece of photosensitive dry film slightly larger than the metal blank.

5. Remove the protective film from one side of the photosensitive dry film using two small pieces

of tape stuck to opposite sides of a corner, and float the remaining photosensitive dry film,

sticky side down, in the pan of water. – The photosensitive dry film seems to lay flatter when

the Mylar film from the inside of the roll is removed first.

6. Remove the metal blank from the pan, place it on a sheet of glass, and spray it with distilled

water.

7. Lift the photosensitive dry film from the water by holding two corners and apply it to the metal

blank. – The film can still be fairly easily moved around at this point.

8. Using light pressure, squeegee the film from the center of the blank to the edges, all around, to

remove most of the water.

9. Trim the film to the edges of the metal blank. – I use an X-Acto knife

10. Place the metal blank on a dry paper towel and squeegee out the rest of the water, from the

center of the blank to the edges, using a fair amount of pressure. Pat the metal blank dry.

11. Sandwich the metal blank between two sheets of plain paper and run the sandwich through a

laminator, one or more times, to help bond the film to the metal. – I run it through my laminator

to a surface temperature of around 150°F.

12. Let the metal blank cool, place the mask on top of the film side of the metal blank, and sandwich

them between two sheets of Plexiglas or glass. – I turn the transparency film over so the ink side

is on the bottom next to the photosensitive dry film. I have found this gives me a crisper edge to

the etching because light cannot angle in under the ink from the side and partially expose the

film under the edges of the mask. I sandwich the blank with the film and the design mask

between two 5”x5” sheets of 1/8" Crystal Clear Cell Cast Plexiglass and hold it together with four

binder clips.

13. Expose the sandwich to an UV light source. – The exposure time is dependent on the film, the

UV light source, and the distance from the light source to the UV film. I have two UV light

sources that I commonly use:

• A Makartt 36W Nail Dryer Gel Curing UV Nail Lamp with the two outside bulbs removed.

My normal exposure time is about 1 minute.


• A desk lamp with an Atshark E27 A19 7W LED UV Ultraviolet Blacklight AC100-240V light

bulb, 5 inches above the sandwich. My normal exposure time is about 2 minutes

14. Remove the metal blank from between the Plexiglas sheets and remove the protective Mylar

film from the top of the photosensitive dry film by sticking a small piece of tape to one corner

and pulling up. – The design will barely be visible in the exposed film at this point.

15. Place the metal blank in a 1-1.5% solution of sodium carbonate and gently wipe away the

unexposed areas of the film. – I use a 1.5% solution of sodium carbonate at room temperature.

I gently wipe the surface with a soft foam paint brush for about 1 minute and then rinse it under

cold running water while gently rubbing any remaining unexposed film away with my fingers.

16. Spray the film with a weak acid solution to stop the development process and rinse with water.

– I use a 3:1 solution of distilled water and white distilled vinegar.

17. Expose the developed film to the UV light again to harden the developed film. – I expose it to

the UV light source for an additional 2 minutes. The film turns even a darker blue/purple than it

was following development.

18. Etch the metal blank.

19. Place the metal blank in a solution of sodium hydroxide to remove the exposed film resist. – I

use a 1.5% solution and let it soak. INSMA generally takes about 5 minutes and Puretch less

than a minute.

Calibrating the UV Light Source

I calibrate my exposure setups using a 21 step Stouffer transmission scale. The picture on the right is the sample exposures I made to calibrate one of my UV light sources. The strip on the left was exposed for 1 minute, the center strip for 2 minutes, and the right strip for 3 minutes. The number of significance is the first number where the little graduated strips are no longer visible and the bare copper is clean. I have found that an exposure number of “6” or “7” works well for me.

Preparing the Sodium Carbonate (Na2CO3) Solution

Caution – Please wear eye protection while preparing and using the sodium carbonate solution.

Sodium carbonate, also known as washing soda, soda ash or soda crystals, may be purchased from most

grocery stores. It may be in the soap/detergent section.

I add 15 grams (about 2 teaspoons) of sodium carbonate to 1 liter of distilled water to make a 1.5%

solution.

Preparing the Sodium Hydroxide (NaOH) Solution

Caution – Please wear rubber gloves, a dust mask, and eye protection while preparing and using the

sodium hydroxide solution.


Sodium hydroxide, also known as lye and caustic soda, may be purchased from many grocery stores or

hardware stores. It may be in the drain cleaner section.

Caution: Dissolving sodium hydroxide is an exothermic reaction. Always add the sodium hydroxide to

the water.

I add 10 grams (a little less than 2 teaspoons) of sodium hydroxide to 1 liter of distilled water to make a

1% solution. Immediately shake or stir the solution to help dissipate the heat being generated.

Other Resist Options

Contact Paper

Contact paper is an adhesive-backed sheet of vinyl available at most hardware stores. I find it very useful

for covering the back of the metal blank. I use clear contact paper because it allows me to see what I am

doing, but non-clear contact paper would work just as well. It stands up well to sodium chloride and

cupric nitrate; however, I have experienced a little seepage under the edge when using copper sulfate as

the electrolyte.

Tape

I have found that Scotch MagicTM tape works very well for covering the edges. Other waterproof tapes,

e.g. packaging tape, electrical tape, etc., also work for covering the edges and the back of the metal

blank. With all tapes watch out for possible leaks from the edges of the areas where the tapes overlap.

Fingernail Polish

Nail polish is good for touching up flaws in the other resists, and for sealing the edges of the metal

blank. I recommend the use of dark colors, as it is easier to see if the coverage is complete.

Nail polish can be removed with acetone, denatured alcohol, and lacquer thinner.

Paint Pens

Regular Sharpies and magic markers do not work well as electro-etching resists; they must be paint pens

or paint markers. Be sure to let the paint dry completely before handling or etching. The brands I have

worked with include:

Craftsmart Paint Pens – Craftsmart Paint Pens are available in several point sizes, including broad and

fine. The Craftsmart Paint Pens paint can be removed with acetone, denatured alcohol, or lacquer

thinner. Note: The some of the Craftsmart Paint Pens I have recently purchased contain xylene and

may dissolve laser toner.

DecoColor Opaque Paint Markers – DecoColor Paint Markers are available in several point sizes,

including broad, fine, and extra fine. The DecoColor Paint Markers paint can be removed with the

DecoColor Paint Marker Remover, lacquer thinner, or turpentine. Note: The DecoColor Opaque Paint

Markers contain xylene and may dissolve laser toner.

Other brands of paint pens that I have tried, but found did not hold up well to electro-etching include:


• Painters by Elmer’s

• Sharpie Oil Based Paint Markers - Sharpie Oil Based Paint Markers are available in several point

sizes, including bold, medium, fine, and extra fine. I have found the “bold” and “medium”

markers are subject to pinholes, and the “fine” and “extra fine” point markers do not hold up at

all.

Electrolytes The most common electrolytes used for electro-etching include:

• Cupric nitrate is my favorite electrolyte. It works quickly, results in a nice smooth etch, etches

silver, and lasts for a long time.

• Sodium chloride works quickly, but often results in a rough etch with striations if the current

density is too high. Sodium chloride does not etch silver.

• Copper sulfate etches the copper alloys, but it does not etch silver, it is slower, and will

sometimes seep under some of the resists, but it lasts for a long time.

• Silver nitrate is more corrosive and more expensive than cupric nitrate, and it has a limited life if

any other metal besides pure silver is introduced into the electro-etching process.

• Sodium nitrate etches silver and the copper alloys. It gives a quick, clean etch, but it needs

filtration often and I am not sure how long it will last as an effective electrolyte..

I will use the chemistry term molality, abbreviated “m”, to express the concentration of the electrolyte

solutions. A 1m solution contains the molecular weight of the solute expressed in grams dissolved in 1

liter of distilled water. Don’t worry about the details. It is just a handy way to identify the concentration

of a solution, but I won’t ask you to figure it out, I’ll tell you what each solution is that I use.

Almost any concentration of electrolyte will work for electro-etching. Weak solutions may just take

longer, and give the resist more time to fail, and very strong solutions may just be a waste of chemicals

if they do not enhance the speed or the quality of the etch. There is nothing magical about the

concentrations I recommend below, they are just what I feel works well for me.

Cupric Nitrate (Cu(NO3)2) A cupric nitrate, also called copper(II) nitrate, solution can be used to etch copper, brass, bronze, nickel

silver, and silver. The cupric nitrate solution will remain active for years without refreshing. A big

advantage is that the cupric nitrate solution can be used to etch silver and the silver can be recovered

from the solution.

When etching silver, I have found that using a saturated solution of cupric nitrate (6.6m solution) does

result in an appreciable increase in the quality of the etching over a 1m solution.

While etching silver a “grayish algae” will form around the cathode and flow out across the bottom of

the container. This “algae” is “pure” silver. If the “algae” flow reaches the anode, the current will short

out and the etching will slow down. I always filter the solution through a coffee filter when returning it

to the storage bottle. I dry the filter paper, and heat the residue with a torch on a charcoal block to melt


the silver into a ball. Silver particles that remain suspended in the solution will slowly settle out to the

bottom of the storage bottle. I try to avoid pouring out the last little bit from the storage bottle when

preparing for the next etching. When the sediment becomes significant, I fine filter it with vacuum

filtration. (See the section on Vacuum Filtering the Electrolyte.)

While etching copper and copper alloys, the copper ions that are removed from the anode will plate out

on the cathode looking like a small forest of pine trees. This is similar to electroforming, except that in

electroforming the current density is probably lower and additives are added to the solution to cause

smoother plating out of the copper.

When etching copper and copper alloys, I have found that using a saturated solution of cupric nitrate

(6.6m solution) does not result in any appreciable increase in the quality of the etching over a 1m

solution.

Preparing the Cupric Nitrate Solution

Caution – Please wear rubber gloves, dust mask, and eye protection while preparing and using the

cupric nitrate solution.

Cupric nitrate may be purchased from The Science Company at www.sciencecompany.com.

The following table shows how much water I add to the size bottles of cupric nitrate sold by the Science

Company to prepare a 1m solution. I prepare the solution the day before and let it sit overnight. This is

not a saturated solution, so there should not be any undissolved cupric nitrate in the bottom of the

bottle.

Grams of Cupric Nitrate

Add Distilled Water Approximate Resulting 1m

Solution

100 grams 0.5 liters 0.6 liters




The following table shows how much water I add to the quantities of cupric nitrate sold by the Science

Company to prepare a saturated (6.6m) solution. I prepare the solution a day ahead of time and let it sit

overnight. There may be a small quantity of undissolved cupric nitrate in the bottom of the bottle.

Grams of Cupric Nitrate

Add Distilled Water Approximate Resulting 6.66m

Solution





http://www.sciencecompany.com/


Disposing of the Cupric Nitrate Solution

A cupric nitrate solution will last for years when handled properly, filtered before returning it to the

storage bottle, and periodically vacuum filtered.

The cupric nitrate solution contains metal salts, and should not be poured down the drain. Please wear

rubber gloves and eye protection when handling the used electrolyte. Contact your local Hazardous

Waste Disposal for proper disposal information if it needs to be disposed of.

Sodium Chloride (NaCl) A solution of sodium chloride (NaCl), also known common table salt, can be used to etch copper, brass,

bronze, nickel silver, aluminum, and steel. The solution is good for several etchings, but it will quickly

begin to form a muddy brown/blue precipitate when electro-etching copper or a copper alloy, or a black

precipitate when electro-etching steel.

Advantages to using a sodium chloride solution to electro-etch include, it is cheap, easy to prepare, and

etches very aggressively. Disadvantages include that it does not last very long, and, after etching, the

electrolyte contains metal salts that should not be disposed of by just pouring the used solution down

the drain.

Adding citric acid to the sodium chloride electrolyte will keep the electrolyte clearer when etching

copper or copper alloys. It does this by locking up the copper ions with a chemical process called

chelation which bonds the copper ions to the citric acid molecule. Eventually the citric acid will become

exhausted and more will have to added, or a new solution prepared.

Very shortly after starting to electro-etching with sodium chloride, hydrogen bubbles will begin rising off

a clean cathode. If the cathode is dirty it will not be as obvious. If bubbles begin to form on the anode it

means the polarity of the circuit is reversed and the leads to the anode and cathode need to be

switched.

Preparing the Sodium Chloride Solution

I prepare a saturated solution of canning and pickling salt with distilled water. Read the label on the

package of salt to make sure there is nothing added, e.g. the anti-caking agent in table salt, or iodine.

The solution will take about 1-1/4 cups (12.5 ounces by weight or 360 grams) of canning and pickling salt

per liter of distilled water (6.2m solution). When I use citric acid in the salt electrolyte I add 2

tablespoons per liter. I prepare the solution the day before and let it sit overnight. There should be a

small amount of undissolved salt in the bottom of the storage bottle.

Using lower concentrations of sodium chloride to electro-etch copper will result in a slower, less

aggressive etching action.

Disposing of the Sodium Chloride Solution

The used sodium chloride solution contains metal salts, including cupric chloride, cupric hydroxide, and

cuprous oxide, and should not be poured down the drain. Please wear rubber gloves and eye protection


when handling the used electrolyte. Contact your local Hazardous Waste Disposal for proper disposal

information

Copper Sulfate (CuSO4) A copper sulfate solution can be used to etch copper, brass, bronze, and nickel silver. The copper sulfate

solution will remain active for years without refreshing. If there are small amounts of precipitate in the

bottom of the tank after etching, simply filter the solution through a coffee filter when returning it to

the storage bottle, and discard the filter paper.

When using copper sulfate as the electrolyte I have experienced seepage under the edges of some of

the resists.

Preparing the Copper Sulfate Solution

Caution – Please wear rubber gloves and eye protection while preparing and using the copper sulfate

solution.

I feel I get the best etch using a less than saturated solution of copper sulfate. I prepare a 0.4m solution

of distilled water with copper sulfate pentahydrate, or Root Killer from a local hardware store. Read the

label on the package to make sure there is nothing added, like an anti-fungal agent. I add about 100

grams (3.5 ounces by weight or 3/8 of a cup) of copper sulfate per liter of distilled water (0.4m solution).

I prepare the solution the day before and let it sit overnight. There should not be any undissolved

copper sulfate in the bottom of the storage bottle.

Disposing of the Copper Sulfate Solution

A copper sulfate solution will last for years when handled properly and filtered before returning it to the

storage bottle.

The copper sulfate solution contains metal salts and must be disposed of properly. Please wear rubber

gloves and eye protection when handling the used electrolyte. Contact your local Hazardous Waste

Disposal for proper disposal information.

Silver Nitrate (AgNO3) Silver nitrate may also be used to etch silver. However, the introduction of copper into the electrolyte,

either from the cathode or by etching sterling silver, will cause silver to precipitate out as metallic silver

and the electrolyte will eventually turn blue and be converted into cupric nitrate.

The silver can be recovered from the silver nitrate solution. Simply filter the solution through a coffee

filter when returning it to the storage bottle, dry the filter paper, and heat the residue with a torch on a

charcoal block to melt the silver into a ball.

Preparing the Silver Nitrate Solution

Caution – Please wear rubber gloves and eye protection while preparing and using the silver nitrate

solution. Silver Nitrate is corrosive and contact can severely irritate and burn the skin and eyes with

possible eye damage. It also causes permanent brown stains on almost everything it touches. The stains

won’t be evident until exposed to UV light.


I prepare the silver nitrate electrolyte by dissolving 10 grams of silver nitrate in 0.5 liters of distilled

water (a 0.1m solution). This is not a saturated solution, so there should not be any undissolved silver

nitrate in the bottom of the bottle.

Sodium nitrate may be purchased from The Science Company at www.sciencecompany.com. 10 grams

will make about 0.5 liters of electrolyte.

Disposing of the Silver Nitrate Solution

Before disposing of the silver nitrate solution place several scrap pieces of copper on the storage bottle

and let it sit for a period of time. The silver to precipitate out as metallic silver and the solution will

eventually turn blue and be converted into cupric nitrate. Filter the solution through a coffee filter and

remove any remaining copper pieces, dry the filter paper, and heat the residue with a torch on a

charcoal block to melt the silver into a ball.

The solution, now a cupric nitrate solution, contains metal salts and must be disposed of properly.

Please wear rubber gloves and eye protection when handling the used electrolyte. Contact your local

Hazardous Waste Disposal for proper disposal information.

Sodium Nitrate (NaNO3)

A sodium nitrate solution can be used to electro-etch silver and the copper alloys. It costs slightly less

that cupric nitrate. The solution is good for several etchings, but it will quickly turn cloudy. The

precipitate is very fine and filtering the solution is very slow. At this time I am not sure of the expected

lifetime of the solution.

Preparing the Sodium Nitrate Solution

Caution – Please wear rubber gloves and eye protection while preparing and using the sodium nitrate

solution.

I prepare the sodium nitrate electrolyte by dissolving about 7 ounces by weight (200 grams) of sodium

nitrate per quart of distilled water (a 2.3m solution). I prepare the solution the day before and let it sit

overnight. This is not a saturated solution, so there should not be any undissolved sodium nitrate in the

bottom of the bottle.

Sodium nitrate may be purchased from The Science Company at www.sciencecompany.com. 500 grams

(about 17.6 oz. by weight) will make about 2.5 liters of electrolyte.

Disposing of the Sodium Nitrate Solution

The used sodium nitrate solution contains metal salts and must be disposed of properly. Please wear

rubber gloves and eye protection when handling the used electrolyte. Contact your local Hazardous

Waste Disposal for proper disposal information.

Power Source Options For many jewelry-sized electro-etching projects a power supply that can deliver up to 6-8 volts and 2-3

amps is sufficient. More power generally results in a faster, but rougher etch. I have found that the key




to a clean, smooth etch is commonly to etch “low and slow”, except for large areas of silver where I’ve

found a high current density is sometimes more effective.

I believe the best overall solution for most electro-etching studios is a commercial rectifier. A rectifier

will provide separate adjustments for both the voltage and the current (amps) to meet most electro-

etching needs. In addition a rectifier will have readouts for both voltage and current, thereby

eliminating the need for a multimeter.

Rectifiers

In my studio I also use a HY1803D Variable Linear Single-Output DC Power Supply, 0-18V @ 0-3A. (These

are found under several different brand names, so just look for the HY1803D model.) This rectifier gives

me excellent control of both the voltage and the current, and allows for very controlled repeatability of

multiple copies of an etching.

Other Power Supply Options I find access to a multimeter essential for measuring the current being supplied to the etching tank with

the other power supply options listed below. A multimeter is an electronic measuring instrument for

measuring volts, ohms, and amperes. When selecting a multimeter be sure to get one that has a scale

for measuring at least 10 amperes. A reasonable multimeter should be available for $10-$20 at places

like Amazon, etc.

Batteries


For the occasional etcher, a pair of alkaline “D” batteries provides plenty of power for electro-etching

pendant and earring sized jewelry. Battery holders for holding 2 “D” batteries, with attached leads with

alligator clips, are available on-line from sites like amazon.com, etc.

The next step up from the 2 “D” battery pack is to a 4 “D” battery pack or a 6 volt lantern battery. There

are tutorials on YouTube that use a small 9 volt battery for electro-etching. However, it has been my

experience that anything smaller than a pair of “D” batteries, e.g. a 9 volt battery, does not have much

of a battery life for electro-etching.

I use alkaline “D” cells and alkaline lantern batteries because they have a slight performance edge over

non-alkaline batteries.

Power Supplies

These are the things that are used to charge electronic devices, power printers and other computer

devices, etc. Some of them can be used to provide power for electro-etching. The most useful ones for

my jewelry work are ones that provide 5-6 volts and 1-1.2 amps of DC current. For etching larger areas,

e.g. backgrounds, ones that provide 9-12 volts and 2-3 amps are useful.

Note: Depending on the area being etched, and other factors, it is possible to draw more current from

some of these power supplies than they are rated for. If this is happening, the transformer will get very

hot, and may actually burn up. Feel the transformer periodically and unplug it if it is getting

uncomfortably hot.

There are two methods of integrating these power supplies into an electro-etching setup. The first is to

modify the power supply, which makes it unusable for its original purpose, and the second is to use a

pigtail, which will allow the power supply to be borrowed and later returned to its original purpose.

Modifying a Power Supply


If you no longer have a use for the power supply, the simplest thing to do is to cut off the plug and

attach alligator clips to the ends of the two wires. Use a multimeter to determine which wire is the

positive side. Attach a red alligator clip to the end of the positive wire, and attach a black alligator clip

to the end of the other wire.

Borrowing a Power Supply

In order to borrow a power supply you will need to purchase or make a pigtail that has a female plug to

accept the plug from the power supply on one end of a pair of wires and a pair of alligator clips on the

other ends of the wires. The most common plug used on the power supplies of interest is what is called

a “2.1 x 5.5mm DC Power Plug”. Search on eBay for something like “Alligator Test Clip Lead to DC Power

5.5x2.1mm Female Adapter”.

Homemade Power Supplies

In my studio I have also used a twin power supply that I constructed from Radio shack parts and a

couple of PC power supplies that allows me to etch in two tanks at the same time. It can provide 5.0

volts at up to 3.0 amps of current to each tank.

Automotive Battery Chargers

For large projects, or production work, consider a larger tank and an automotive battery charger. The

key here is to select a manual battery charger, rather than an automatic charger with automatic shutoff,


trickle charging, etc., unless you know exactly how those functions work. You do not want to have the

charger decide for itself that the job is done half way through the etching cycle.

Note: Be aware when using setups like this, where a large amount of current is being used, that the

electrolyte will heat up, sometimes to a rather surprising temperature. This may affect some wax based

resists in a negative manner.

Metals The metals I have personal experience electro-etching include:

• Copper (Cu)

• Silver (Ag)

• Aluminum (Al)

• Nickle Silver, a.k.a. German Silver

• Red Brass, a.k.a. Jeweler’s Brass, NuGold, Jeweler’s Bronze, or Merlin’s Gold

• Bronze

• Steel

Before applying the resist I make sure the metal blank is flat, scrub it lightly with Penny Brite to remove

any oxidation, and wipe it with denatured alcohol or acetone to remove any oils or grease. Rubbing

alcohol and fingernail polish remover are not good substitutes for denatured alcohol and acetone. They

contain oils and other ingredients to make them less harsh on skin, and these oils, etc. may be left

behind on the surface of the metal.

Copper Copper can be electro-etched using sodium chloride, copper sulfate, or cupric nitrate as the electrolyte.

Silver Silver can be electro-etched using cupric nitrate, silver nitrate, or sodium nitrate as the electrolyte.

When etching silver with cupric nitrate, a “grayish algae” will form around the cathode and flow out

across the bottom of the container. This “algae” is “pure” silver. If the “algae” flow reaches the anode,

the current will short out and the etching will slow down. I always filter the solution through a coffee

filter when returning it to the storage bottle. I dry the filter paper, and heat the residue with a torch on

a charcoal block to melt the silver into a ball. Silver particles that remain suspended in the solution will

slowly settle out to the bottom of the storage bottle. I try to avoid pouring out the last little bit from the

storage bottle when I am preparing for the next etching. When the sediment becomes significant I fine

filter it with vacuum filtration. (See the section on Vacuum Filtering the Electrolyte.)

Aluminum Aluminum can be electro-etched using sodium chloride or cupric nitrate as the electrolyte. A pure

copper sulfate electrolyte will not etch aluminum.


Electro-etching aluminum in a 1m sodium chloride solution resulted in a smooth and even etch. Electro-

etching aluminum in a 6m sodium chloride solution is very aggressive and results in a rough etch.

Bubbles will appear on both the cathode and the anode when electro-etching aluminum in a sodium

chloride solution. It is reported in the literature that electro-etching aluminum in a sodium chloride

solution produces hydrogen gas the cathode and chlorine gas at the anode. The quantities of chlorine

gas are very small, but please take proper precautions, work in a well ventilated area, and keep your

face away from the etching tank.

I do not reuse the electrolytes used to electro-etch aluminum because I do not know what effect the

aluminum salts they may now contain will have on future etching of other metals.

Nickle Silver (a.k.a. German Silver) Nickle silver is an alloy of copper (65%), nickle (18%), and zinc (17%). (CDA #752 alloy)

Nickle silver can be electro-etched using sodium chloride, copper sulfate, or cupric nitrate as the

electrolyte.

Red Brass (a.k.a. Jeweler’s Brass, NuGold, Jeweler’s Bronze, or Merlin’s Gold) Red Brass is an alloy of copper (85%) and zinc (15%). (CDA #230 alloy)

Red Brass can be electro-etched using sodium chloride, copper sulfate, or cupric nitrate as the

electrolyte.

Bronze Bronze is an alloy of copper (92%) and tin (15%). (CDA #521 alloy)

Bronze can be electro-etched using sodium chloride, copper sulfate, or cupric nitrate as the electrolyte.

Steel My experience to date has been with low-carbon steel.

Steel can be electro-etched using sodium chloride as the electrolyte.

Electro-etching steel with sodium chloride results in fairly vigorous reaction, with lots of dark precipitate

being generated.

Preparing the Package for Etching

Etching the Background (relief etch) vs Etching the Design (intaglio etch) Typically a design will be much smaller in area than the area of the background (negative space)

surrounding the design. This means that designs (intaglio etch) can usually be etched faster, and at a

lower current, than background (relief etch). My method of preparing the package for etching depends

on the resist and whether it is intaglio or relief etching.


Relief Etching with All Resists

For relief etching, the only part of the metal that is covered with resist is the design area that is not to be

etched, and the back of the metal blank. All the rest of the metal blank will be exposed to the

electrolyte and will be etched.

1. Prepare the metal blank by scrubbing it well, and wiping it with denatured alcohol. Do not bother to smooth the edges at this time. The edges will be etched and will need to be smoothed after the etching process. Apply the resist to the face of the metal blank.

2. Apply the resist to the face of the metal blank.

3. Cut a piece of contact paper slightly wider and about an inch taller than the metal blank. Cut a small horizontal slit in the contact paper near the top of where the metal blank will be. The slit needs to be wide enough to slip the aluminum strip through, but narrower than the width of the metal blank.

4. Remove the backing from the contact paper. Slip about half an inch of the aluminum strip through the slit from the non-sticky side to the sticky side, and stick the end of the aluminum strip to the sticky side below the slit. (For the photo, I set it down on the backing paper so it would not stick to my background.)

5. Turn the metal blank over so the design is on the bottom and place it on the saved backing paper. Apply the contact paper to the back of the metal blank with the extra inch being on the top of the metal blank, and burnish it to the metal.

6. Cut another piece of contact paper large enough to cover the aluminum strip from below the slit to the top of the first contact paper. Burnish it onto the first contact paper and the aluminum strip to prevent the electrolyte from getting to either the slit or the aluminum strip.


7. The package is now ready to be etched. Be sure the electrolyte does not touch any of the exposed aluminum strip when it is in the tank.

Intaglio Etching with Vinyl Resist

For intaglio etching, the only part of the metal that is exposed to the electrolyte is the area to be etched.

All the rest of the metal blank, and the aluminum contact strip, need to be covered with resist.

1. Prepare the metal blank by smoothing the edges with fine sandpaper, scrubbing it well, and wiping it with denatured alcohol.

2. Remove the border around the frame containing the design to be etched. Weed the parts of the design that are to be etched using a dental pick, needle, or sharp pointed tweezers.

3. Cut a length of Scotch MagicTM tape long enough

to cover the design, place the tape on top of the design in the mask, and burnish the tape to the vinyl. It may take more than one strip of tape to cover the design. If so, overlap the strips of tape slightly.

4. Carefully peel the backing paper away from the vinyl exposing the sticky side of the vinyl. Hint: Keep the backing paper to use as a base when you apply the mask to the earring blanks in the next step.

5. Hold the mask so the sticky side is down, place the design on the metal blank, and press the vinyl down onto the metal. Burnish the vinyl to the metal.

6. Turn the package design side down, take a small

strip of aluminum foil and lay it so that it touches the metal blank with the rest of the strip sticking out the top of the mask. Press the aluminum strip down so that it sticks to the vinyl.


7. Cut a piece of contact paper the same size as the frame. Lay it on the back of the package, covering the metal blank and the aluminum foil strip. Burnish it onto the back of the package, and burnish all the edges to the sticky side of the vinyl to prevent any electrolyte from leaking in.

8. Turn the package design side up and carefully remove the tape, or tapes, one at a time, in the reverse order of how they were applied. Make sure none of the design pulls off the metal with the tape. Burnish the vinyl to the metal again just in case anything pulled loose when the tape was removed.

9. The package is now ready to be etched. Be sure the electrolyte does not touch any of the exposed aluminum strip when it is in the tank.

Intaglio Etching with Photosensitive Dry Film or Toner Resist

When using a photosensitive dry film, or toner, resist for intaglio etching I have found it difficult to get

good resist coverage right at the edges, and on the edges, of the metal blank. I give special attention to

the edges, as well as large areas of the resist that may have pinholes.

1. Apply the photosensitive dry film, or the toner, to the metal blank.

2. Prepare the package as described above for Relief Etching with All Resists

3. Seal the edges using strips of Scotch MagicTM tape

to cover all the edges, sealing the resist to the contact paper backing, or liberally apply nail polish to the edges, being careful not to cover any of the design that is to be etched.


I examine both toner and photosensitive dry film resists under magnification and apply nail polish to any

pinholes. I also commonly cover large areas of toner with nail polish just to be on the safe side in case I

missed any pinholes.

Q-Tip Etching Q-tip etching is a quick and simple way to put a mark on metal. For example, it can be used for etching

your name, or maker’s mark, on a knife blade, jewelry, or some other metal object. All that is needed is

a Q-tip, a suitable resist mask, a power source, and a teaspoon of electrolyte.

Q-Tip etching can also be used to touch up a larger etching where an air bubble, or something similar,

prevented a small area from being etched.

The process is simple.

1. Apply the resist mask to the metal object. For this demonstration I am using a laser toner mask on a scrap piece of copper applied using PnP Wet paper.

2. For this demonstration, I am using a 9V 2A power supply and a pig tail.

3. Attach the positive lead (red) from the power source to the metal to be etched. Attach the negative lead (black) from the power source to the cotton ball at the end of a Q-tip.

4. Soak the cotton ball at the end of the Q-tip in the electrolyte and apply it to the area to be etched. Repeat until the etching is the desired depth.


5. Remove the resist mask with acetone. It took less than a minute to etch my maker’s mark into the copper.

Etching from Photographs

Colorscape App There is an app available on Apple iPads and iPhones called Colorscape. Colorscape takes a photograph

and turns it into a coloring page. You may further modify the result using a photo editing program if

desired. The final result can then be used as a design for etching.

For example, the following photographs were run through Colorscape, printed on PnP Wet, and used as

the resist for electro-etching the copper plaques.


Background Removal using Microsoft Powerpoint Microsoft Powerpoint has a feature, called “Remove Background”, that may be used to remove

unwanted background before using Colorscape to create the etching design.

My original picture contained a very cluttered background

Passing the original picture through Colorscape produced the following unsatisfactory result.

Instead, I used the Remove Background feature of Powerpoint on the original photo to produce the

following picture.


I then ran the picture with the background removed through Colorscape on my iPad and produced the

following satisfactory pattern for etching.

Vacuum Filtering the Electrolyte Electro-etching silver with cupric nitrate results in most of the silver that was etched from the silver

anode, forming a black, or silver, cloud in the bottom of the etching vessel that can easily be recovered

by filtering the electrolyte through a coffee filter when it is returned to the storage bottle. However

some of the silver will remain suspended as a colloid in the cupric nitrate, where, after a while, it will

begin to interfere with the etching process. The colloidal silver is very visible by shining a flashlight into

the electrolyte from the side. The electrolyte will appear to be full of silver glitter.

This colloidal silver is too small to be removed using coffee filters and needs to be removed by

periodically vacuum filtering the electrolyte through a finer filter paper. This is really a simple process,

but it involves some specialized equipment. What is needed is a Filter Flask Set, including the flask,

funnel, stopper and filter paper, and a small vacuum pump.


1. Place the funnel, inserted through the stopper, into the neck of the flask.

2. Place a piece of filter paper in the funnel.

3. Connect the vacuum pump to the flask.

4. Fill the funnel with the electrolyte to be filtered.

5. When the liquid stops flowing, give the vacuum pump a couple of pumps to pull the liquid through.

6. When a slight vacuum no longer works, change the filter paper.

Note: Be careful not to apply too much vacuum or you will tear holes in the filter paper.

Refer to the Electro-Etching Studio Equipment section to see the equipment that I use.

Burnishing with a Tumbler An easy way to polish small jewelry items is to burnish them in a small tumbler with stainless steel shot

and a burnishing liquid. I have found that 30 minutes is usually adequate for most sterling silver, gold

filled, copper, and brass items.

I use a Lortone Model 3-1.5B tumbler in my studio and a small tumble from Harbor Freight

(manufactured by Chicago Electric Power Tools) in some of my classes and workshops.

I use the barrel from the Lortone tumbler (it is a little smaller than the Chicago Electric barrel), and 2

pounds of the Stainless Steel Mixed Shot (Rio Grande #339-097) with Super Sunsheen Burnishing

Compound (Rio Grande #339-394). Make sure you get stainless steel shot or you will spend all your time

trying to keep it from rusting.

In my studio, I leave the shot in the barrel, covered with fresh water and Super Sunsheen, between

tumbling runs. After tumbling for 30-45 minutes I dump the contents of the barrel into a colander,

remove the items I was burnishing, and rinse both the shot and the tumbling barrel thoroughly with

water. I pour the shot back into the barrel and cover the shot with fresh water and Super Sunsheen and

it is ready for next time.

I have heard people say that they have had trouble with “black gunk” appearing in their tumbler and on

their finished pieces. I feel this is usually due to dirt from running the tumbler too long without

changing the liquid, and not due to the rubber of the barrel breaking down. I have not had this problem

for many years now, ever since I started changing the burnishing liquid after every use.

Students have asked about household products they can use instead of Super Sunsheen. I have tried

several products recommended by others, but I have not found anything that will give me the results


that I get from Super Sunsheen. Super SunSheen is diluted 45 to 1 for use. A 1 quart bottle of Super

Sunsheen will last me for over 200 tumbler runs, and only costs a couple of cents per run. I just don’t

think it is worthwhile spending the time or money to try anything else.

I use Goddard’s Silver Polish liquid (#707184), or Goddard’s Silver Polishing Cloth (#707684), to put the

final shine on my finished silver pieces.

Coating Base Metal Jewelry I normally do not like to coat my jewelry because I am not sure of the lifespan of the coating and

because there are cleaning solutions and polishes out there that will harm the coating, and I do not like

dealing with upset customers.

But sometimes, particularly with base metals, it is desired/required to slow tarnishing and preserve the

patina and/or coloring. Just make sure you tell the customer that it is coated.

The best method that I have found so far is ProtectaClear® by Everbrite. Complete product instructions

are available at www.everbritecoatings.com/Quickstart_Jewelry.pdf.

To summarize the method that I use:

1. Polish the jewelry piece

2. Rinse with water and dry

3. Wipe with denatured alcohol to remove grease and fingerprints

4. Hang the jewelry piece from a very thin wire

5. Pour the ProtectaClear into a small glass jar, NOT plastic

6. Dip the jewelry piece by bringing the jar up under the piece to submerge it in the liquid

7. Lower the jar and pour the liquid back into the storage container

8. Set the jar under the jewelry piece to catch any drips

9. Check the jewelry piece after a minute or two and remove any liquid that has collected on the

bottom with a clean dry brush, repeat as needed

10. Repeat the dipping after an hour or so if a second coat is desired

11. The coating will be fully cured in 4 to 5 days

12. The curing can be forced, after a couple of hours of drying, by placing it in a 180°F oven for

about an hour

Electro-Etching Studio Equipment This is a list of the equipment in my etching studio that I make the most use of.

Etching station:

http://www.everbritecoatings.com/Quickstart_Jewelry.pdf


• Rectifier - HY1803D Variable Linear Single-Output DC Power Supply, 0-18V @ 0-3A. (These are

found under several different brand names, so just look for the HY1803D model.) –

www.amazon.com

• Tanks – Felli® Flip Tite Acrylic Food Storage Canisters – search on the web

• Electrolyte – Cupric Nitrate (Cu(NO3)2) from The Science Company – www.sciencecompany.com

• Degree Gauge – used to measure the depth of the etch during the etching process –

item 116008 or 115028 from www.riogrande.com

• Digital Timer for timing the etching process – RadioShack® 10-Key Count-Up and Count-Down

Timer – www.radioshack.com

• Coffee filters and funnel – for filtering the electrolyte as it is poured back into the storage

container

Vinyl station:

• Silhouette Cameo and SilhouetteStudio – available from www.amazon.com

• Transparent vinyl – from either eBay or Amazon, sold by Paper Street Plastics

• Dental picks and pointed tweezers – for weeding the vinyl

• Penny Brite, Denatured Alcohol, and Acetone – for cleaning the metal before applying the vinyl

– hardware Store and www.amazon.com

• Teflon Sheet – to keep the vinyl, transfer tape, and contact paper from sticking to the work

surface while applying the resist to the metal – www.amazon.com

• Scotch Tape – for transferring the weeded design to the metal blank

• Aluminum Foil, heavy duty – used to attach the anode to the positive (red) lead from the power

source

• Clear contact paper and Scotch Tape – for sealing the back of the metal blank and the aluminum

foil lead – local hardware store.

Toner station:

• HP LaserJet P1102w – from www.amazon.com

• Press-n-Peel (PnP) Wet or Toner Transfer Paper - from Electronix Express at www.elexp.com

and www.pcbfx.com

• Penny Brite, Denatured Alcohol and Acetone – for cleaning the metal before applying the vinyl


• Promoheat Press – P230B – for applying the toner to the metal, available from

www.amazon.com

• Aluminum Foil, heavy duty – used to attach the anode to the lead from the power source


foil lead – hardware store.

• Nail Polish and Paint Pens – for covering pinholes in toner and sealing edges. – drug stores,

hobby stores, etc.

Photosensitive Dry Film station:

http://www.amazon.com/


http://www.riogrande.com/

http://www.radioshack.com/





http://www.elexp.com/





• HP Officejet 4620 - www.amazon.com

• Waterproof Inkjet Transparency Film 8.5 x 11 - www.amazon.com

• Penny Brite, Denatured Alcohol and Acetone – for cleaning the metal before applying the vinyl


• Photosensitive Dry Film –

o INSMA PCB Photosensitive Dry Film for Circuit Production Photoresist Sheets –

www.amazon.com. I have not found any processing instructions available from either

the manufacturer or distributers of this film. Instructions are available from a user of

the film at http://www.johncon.com/john/PCB/.

o Puretch – www.capefearpress.com. Processing instructions are available from a

distributer at http://polymetaal.nl/siteUK/Linkdocs/Puretch/modepuretch.htm.

• UV light sources:

o Makartt 36W Nail Dryer Gel Curing UV Nail Lamp with Sliding Tray and 4 Pcs Nail Bulbs –

www.amazon.com

o Atshark E27 A19 7W LED UV Ultraviolet Blacklight AC100-240V – www.amazon.com

• Stouffer 21 Step Sensitivity Guide T2115 – FLD Discount Supplies – www.pcbsupplies.com

• 1/8" Crystal Clear Cell Cast Plexiglass – www.delviesplastics.com

• GBC HeatSeal H220 Laminator – www.amazon.com

• Aluminum Foil, heavy duty – used to attach the anode to the lead from the power source –

grocery store


foil lead – hardware store.

• Chemicals:

o Sodium Carbonate (Washing Soda) – grocery store

o Sodium Hydroxide – Pure Lye from a grocery store or www.amazon.com

Cleaning station:

• Acetone – for removing toner, nail polish, and paint pen paint – hardware store

• Lacquer Thinner – for removing toner, nail polish, and paint pen paint – hardware store

• Penny Brite – for removing stains from copper and brass – www.amazon.com

Filtering station for periodically fine filtering the cupric nitrate:

• Filter Flask Set, 500ml with Funnel, Stopper and Filter Paper – sold by Mountain Home

Biological – www.amazon.com

• Hand Vacuum Pump – sold by Mountain Home Biological – www.amazon.com

Miscellaneous:

• Model SP5 Digital Postal Mailing Scale – for weighing chemicals - www.amazon.com

• Etekcity Lasergrip 1080 Non-contact Digital Laser Infrared Thermometer – www.amazon.com





http://www.johncon.com/john/PCB/

http://www.capefearpress.com/

http://polymetaal.nl/siteUK/Linkdocs/Puretch/modepuretch.htm



http://www.pcbsupplies.com/

http://www.delviesplastics.com/









• Polypropylene Beakers with Handle – for mixing electrolytes from Carolina Biological Supply

Company - www.carolina.com

• ProtectaClear by Everbrite – for coating jewelry if needed – www.amazon.com

MSDS for Common Etching Chemicals and Resulting Products I will not make any comments on the safety, or effectiveness, of any of these chemicals. Please read all

the information and make up your own mind.

I believe the important MSDS sections to look at include Hazards Identification, First Aid Measures,

Handling and Storage, Exposure Controls, Personal Protection, and Disposal Considerations.

Ammonium Persulfate – http://www.sciencelab.com/msds.php?msdsId=9922930

Chlorine gas - https://www.airgas.com/msds/001015.pdf

Copper Sulfate - http://www.sciencecompany.com/msds/Cupric_Sulfate_MSDS.pdf

Cupric Chloride – http://www.sciencelab.com/msds.php?msdsId=9923592 Note: The used sodium

chloride electrolyte from electro-etching of copper, and all copper alloys, contains cupric hydroxide.

Cupric Hydroxide - https://www.sciencelab.com/msds.php?msdsId=9923594 Note: The precipitate

formed during electro-etching of copper, and all copper alloys, with a sodium chloride electrolyte

contains cupric hydroxide.

Cupric Nitrate - http://www.sciencecompany.com/msds/Cupric_Nitrate_SDS.pdf

Cuprous Oxide - http://www.sciencelab.com/msds.php?msdsId=9923605 Note: The precipitate formed

during electro-etching of copper, and all copper alloys, with a sodium chloride electrolyte, contains

cuprous oxide.

Ferric Chloride - http://www.sciencecompany.com/msds/Ferric_Chloride_MSDS.pdf

Ferric Nitrate - http://www.sciencecompany.com/msds/Ferric_Nitrate_SDS.pdf

Hydrochloric Acid - http://www.sciencecompany.com/msds/Hydrochloric_Acid_10percent_MSDS.pdf

Note: The fumes given off while etching aluminum with a mixture of hydrochloric acid (muriatic acid)

and hydrogen peroxide contain chlorine gas.

Hydrogen Peroxide - http://www.sciencelab.com/msds.php?msdsId=9924299

Muriatic Acid – see Hydrochloric Acid

Nitric Acid - http://www.sciencecompany.com/msds/Nitric_10_percent_MSDS.pdf

Phosphoric Acid - http://www.sciencecompany.com/msds/Phosphoric_Acid_85_percent_MSDS.pdf

http://www.carolina.com/


http://www.sciencelab.com/msds.php?msdsId=9922930

https://www.airgas.com/msds/001015.pdf

http://www.sciencecompany.com/msds/Cupric_Sulfate_MSDS.pdf


https://www.sciencelab.com/msds.php?msdsId=9923594

http://www.sciencecompany.com/msds/Cupric_Nitrate_SDS.pdf


http://www.sciencecompany.com/msds/Ferric_Chloride_MSDS.pdf

http://www.sciencecompany.com/msds/Ferric_Nitrate_SDS.pdf

http://www.sciencecompany.com/msds/Hydrochloric_Acid_10percent_MSDS.pdf


http://www.sciencecompany.com/msds/Nitric_10_percent_MSDS.pdf

http://www.sciencecompany.com/msds/Phosphoric_Acid_85_percent_MSDS.pdf


Phosphoric Prep & Etch - http://www.kleanstrip.com/uploads/documents/GKPA30220_SDS-401.5.pdf

Rio Etching Mordant Copper - http://media1.riogrande.com/Content/Copper-Etching-Mordant-

MSDS.pdf

Rio Etching Mordant for Silver - http://media1.riogrande.com/Content/Silver-Mordant-MSDS.pdf

Silver Nitrate – http://www.sciencecompany.com/msds/Silver_Nitrate_SDS.pdf

Sodium Chloride - http://www.sciencecompany.com/msds/Sodium_Chloride_MSDS.pdf Note: The used

sodium chloride electrolyte from the electro-etching of copper, and all copper alloys, contains cupric

chloride, cupric hydroxide, and cuprous oxide. The fumes given off while electro-etching aluminum with

a sodium chloride electrolyte, may contain chlorine gas.

Sodium Persulfate – http://www.sciencelab.com/msds.php?msdsId=9927601

Thank you for attending my workshop. I hope you enjoyed the workshop and get many years of enjoyment using these techniques.

There is a wealth of electro-etch information available on our Web site at www.bijoux-de-terre.com.

Just click on “For Our Students” on the left and “Electro-Etching” near the top center. The latest version

of this handout is also available there.

There is also a Facebook group called “Electro-Etchers Anonymous” that deals with the subject.

If you have any questions, please email me at [email protected].

http://www.kleanstrip.com/uploads/documents/GKPA30220_SDS-401.5.pdf

http://media1.riogrande.com/Content/Copper-Etching-Mordant-MSDS.pdf

http://media1.riogrande.com/Content/Copper-Etching-Mordant-MSDS.pdf

http://media1.riogrande.com/Content/Silver-Mordant-MSDS.pdf

http://www.sciencecompany.com/msds/Silver_Nitrate_SDS.pdf

http://www.sciencecompany.com/msds/Sodium_Chloride_MSDS.pdf


http://www.bijoux-de-terre.com/

mailto:[email protected]

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