Methods of Core Preservation

Phil Rumford Superintendent, Gulf Coast Repository

Meeting of the Curators of Marine and Lacustrine Geological SamplesEstes Park, Colorado. September 2007

A Simple Method• Polyethylene Bag • Oxygen Absorbing Pack• Bag Sealer

AdvantagesCheap

Packs can absorb up to 200cc of O2

Retards mold, mildew, and bacterial growth

DisadvantagesMethods success relies on barrier qualities of bagMessy, labor intensive, difficult to store

More Sophisticated• Use an aluminized bag as an effective O2

barrier

• Flush bag with N2, add O2 pack, and core section

• Heat seal bag

Problems

• Expensive

• Time consuming• Difficult to know when bag is properly

flushed with N2

• Requires skilled/patient user

• Tried on ODP Leg 169 on sulfide rich cores, and was not successful

Vacuum Sealing

• No Aluminized bags

• No N2 flushing or O2 packs

• Simply vacuum seal the corewith a good barrier film

• Small table top models (as shown)cost @ $2.5K

• Works great on hard rock samples with very little moisture content

• Negates the need for d-tubes, increasing available storage area

Problems

• Nozzle type sealers will not give an adequate seal on wet sediment cores.

• The prolonged exposure to vacuum that is necessary on sediment cores may desiccate material and ruin delicate structures

• Use of this method on the RV Chikyu was not successful

Possible Solution

• Food industry useschamber vacuum sealers to vacuum seal wet goods

• Chamber sealers are expensive and not commercially available in the size needed for cores

• May still have the problems of desiccation and physical damage to the cores

Shrink FilmBenefits• Has no effect on sample• Excellent barrier films available cheaply• Equipment readily available - cheap and reliable• Equipment easily tailored to fit budget and work-

load• Negates the need for d-tubes, increasing

available storage area• Allows clear view of core after wrapping

Types of Equipment Available

Basic systems available for under $200

Manual L-Bar Sealers Cost used $2-5K

3

Automatic Side Seal WrapperCost $30-70K

The side seal wheel is shown below

It seals the long axis of the bi-fold film

The bar sealer seals and cuts the leading and trailing edges of the film.

It is operated by a photocell that can detect the presence of the core liner.

The in-feed conveyor and film feed mechanism

Tashina feeds a core section into the machine

The core section being wrapped

The core section enters the heat tunnel

The wrapped section

D-tube storage racks at the GCR

Wrapped cores without d-tubes in close packed storage

Type of film used by IODP

• Cryovac BDF20001

• Good O2 and water vapor barrier

• Easy to use, will shrink and re-shrink

• Gives a clean clear finish

• Costs – about $0.12 per 1.5m section to wrap

Future of Plastic Film

• Rapidly evolving technical field (nanotechnology in plastics)

• Driven by pharmaceutical and food industries

• New types of film constantly being produced

New O2 Scavenging Film from Cryovac

The scavenging component of OS films is an invisible layer of the packaging. A patented UV light triggering process starts the scavenging to remove residual oxygen up to 10 - 20% faster than ever before.

With faster scavenging, your products will retain their high quality longer by slowing oxidative deterioration of efficacy, integrity, reliability, potency and freshness.