Sept., 1918.1 ROBSON-“ STANDARDISING THE FASTNESS OF COLOURS TO LIGHT.” 185

SYLLABUS OF LECTURES FOR WE WINTER SESSION, 1918-191 9.

WEST RIDING SECTION. Thursday, Sept. 26th, 1918.

Thursday, October 3rd.

Wednesday afternoon, Oct. 9th.

and Co. Ltd., Huddersfield.

C. F. Cross, F.R.S., President of the Society.

‘‘ Smoker.”

Visit to works of Messrs. L. B. Holliday

Prof. G. F. Charnock, M.Inst.C.E., Pro- fessor of Engineering, Bradford Technical College. ‘‘ Welding Processes with Special Reference to Machinery Repairs.”

E. Atkinson, Bradford. ‘‘ Some Considera- tions in the Designing of Fabrics.’’

ing and Dyeing with Volatile Solvents.”

Wednesday, Oct. 16th.

Thursday, Oct. 31st.

Thursday, Nov. 14th.

Thursday, Nov. 28th.

Harry Hey, Dewsbury.

W. Greaves, F.I.C., Leeds. ‘‘ Modern Methods of Extraction and Manufacture of Benzol Homologues and Naphthalene.”

“ Notes on Clelein-

Thursday, Dec. 12th.

Thursday, Jan. 9th, 1919.

of Cotton Piece Goods.” Thursday, Jan. 23rd.

S. A. Shorter, D.Sc., of Leeds University.

A. C. Walsh, Bradford. “The Bleaching

Discussion on “ Drying,” opened by Messrs Fred Smith, Morley, Walter Leach, Bradford and J. E. Brierley, of Messrs. The Sutcliffc Ventilating and Drying Co. Ltd., Marichester

H. H. Hodgson, M.A., B.Sc., Ph.D. Bradford. ‘‘ Technical Education and Itc Relation to Industry.”

Prof. J. W. Hinchley, F.I.C., Imperia College of Science and Technology, London “ Filtration.”

H. T. Calvert, D.Sc., Ph.D., F.I.C., Wesi Riding Rive;rs Board, Wakefield. “ Efflu ents.”

H. M. Dawson, D.Sc., Ph.D., Leeds Urii versity. “The Estimation of Mixtures o Isomers and other Closely Related Sub stances.”

Thursday, April 3rd. Discussion on “ The Finishing of Textilc

Fabrics,” opened by W. Harrison, M.Sc. Leeds University.

Thursday, Feb. 6th.

Thursday, Feb. 20th.

Thursday, March 6th.

Thursday, March 20th.

__

HUDDERSFIELD SECTION. The following lectures have been arranged bg

the Committee of the newly formed Huddersfielc Section. Friday, Oct. 4th, 1918.

J. P. King and J. Chambers. “Wate Softening for Textile Purposes.” A6

Friday, Nov. 8th.

Friday, Dec. 6th. T. H. Dean.

E. Midgley. “The Influence of Dyeing and Finishing on Woven Fabrics.”

“The British Dyestuff In- dustry and Its Possible Developments.” Arrangements are also being made for lectures

jo be given by the President (Mr.’C. F. Cross) md Dr. S. A. Shorter. Subjects of these lectures will be given later.

It is also intended to hold a social evening :arly in February, 1919.

COMMU NlCATlON. - The following paper was submitted under the

Prize Problem Scheme of the Society, in com- petition for Problem No. 34, 1916-17 :-

A Method of Standardising the Fastness of Colours to Light.

By ALICE ROBSON, B.Sc. The most usual way of estimating the fastness

Lo light of dyed colours is by comparing them with some colour generally recognised as fast, such as Indigo, and then classifying them, according to the comparison, into such groups as “fast,” ‘‘ moderately fast,” or L L not fast.” The following quotation illustrates this method :

“ If tests for fastness to light have to be made frequently, i t is well to have samples of shades which can be used for comparison ; these must, of course, be themselves very fast.” (Blucher’s “ Modern Industrial Chemistry,” trans , Milling- ton .)

It is obvious that no exact classification can be arrived a t along these lines, and in the following method an attempt is made to standardise colours by comparing them, not with a fast colour, but with a fugitive one. The very small degree of fastness possessed by the latter is taken as the unit, and the light- fastness of other colours is expressed in terms (multiples or, occasionally, fractions) of this unit.

Choice of a Ufiit Co1our.-Slips of filter paper, dyed with various basic and salt colours, un- developed Priaiuline, &c., were exposed t o light. Finally Eosine GCF (Cassella) was chosen. Paper slips tinted a medium pink with this colour were bleached white by exposure to light, behind a glass window, for one week of average early spring weather. (Note.-To choose a colour not easily obtainable in this country a t present may seem to be 5 mistake, but no other dyestuff of those tried fulfilled the two-fold condition of fading quickly and to a clear white. It may also be pointed out that a very small laboratory sample of Eosine GGF will dye an enormous stock of paper slips.)

Preparation of Standard Test Papers.-Pieces of coarse white filter paper were steeped in a 0-1 per cent. solution of Eosine GGF, dried without rinsing, cut into slips measuring 3 in. by 4 in., and stored for future use.

186 ROBSON-“ STANDARDISING THE FASTNESS OF COLOURS TO LIGHT.” [Sept., 1918.

Expowre of Dyed Pattems.Aotton yarn dyed with the various colours to be tested was wound on to cardboard strips, each of which (planned to hold 12 patterns) was placed lengthwise in a thick cardboard envelope covering half of each pattern. A slip of the standard Eosine paper, iiumbered (1) on the under side, was clipped on to the edge of the pattern strip, and the whole was exposed to light against a south window.

(Note.-The patterns and test paper could, o? course, be used equally well in a photographic printing frame if more protection from atmo- spheric influences were desired.)

Daily examination of the patterns is necessary. As soon as the first test-paper slip is found to be bleached, it is removed and substituted by another marked (2), and so on. As soon as a distinct difference in tone or depth of colour is clearly apparent in any one of the patterns, a number can be marked against i t corresponding to the number on the test paper. In practice i t was found that fractional numbers had to be used ; Congo Red faded in about a quarter of the time required to bleach the first test paper, and a number of others were half-way between the removal of the &st and second test papers. These have accordingly been marked 14 on the table submitted herewith.

The advantage of the foregoing method is its independence of weather conditions. The patterns may be exposed for a longer or shorter time according to the season, but if the com- parison is always made with the one standard colonr the number of hours of bright sunshine need not be specially considered.

If for any reason the daily examination of the patterns is interrupted, the cards can be taken from the window and stored in the dark for a few days, to be exposed again later.

The accompanying table shows the result of applying this method of standardisation t o about 50 colours of various classes. It will be noticed that they are mainly cotton dyes. There seems to be no reason, however, why the method should not be applicable to wool 01 silk colours, or to the comparison of the relative fastness of one colour dyed on different fibres as shown in the case of Thio Indigo Scarlet R in the table.

LIGHT EXPOSURE TESTS. EOSINE STAXDAR~.

ClES8. Name of Coloor and X used. Standard No Direct ... Congo Red 30/, . . . . . . . . . f

Congo Rubin 3% 4 ... Congo Corinth 3% . . . . . . . . . 1 1 ... Erika B 0.5% . . . . . . . . . 34

... Rosanthrene CB 3% . . . . . . 1

Diazo ... Primuline dev. ,9 Naphthol 30/, ... 1 vat ... Thio Indigo Scarlet It on silk ... 5

... Tllio Indigo Scarlet R on artificial

... Cotton Yellow CH 1% . . . . . 5

... Dianol Yellow ARX 1%

... Pyrogene Yellow 0 5% . . . . . . 2

... . . . . . . . . .

Diazo ... Rosanthrene Bordeaux B 3% ... 1

VaJ\lndigoicl) Thio Indigo Scarlet R on wool ... 5

silk . . . . . . . . . . . -11 Direct ... Chrysamine K 19’0 . . . . . . . . . 5

. . . . . . 5 Sulphur ... Thionol Yellow G 596 . . . . . . 1

7

Clntse. Name of Colour and X used. Standard No. ... . . . . . . . Sulphur Sulphol Yellow JR 5% 4 ... Hydrosulphon Yellow Y 5% ... g

3asic ... Auramine 1% . . . . . . . . . 2 3irect ... Direct Blue 2B lyo . . . . . . 1

... Dianol Blue G 1% . . . . . . . . . 6

... Chloramine Blue 3G 1 . . . . . . 1 ,, ... Chlorazol Blue WB 12 . . . . . . 14

... Pyrogene Blue Green shade 5% 1:: it ... ... ?

Sulphur ... Pyrogene Direct Blue RL 5%

... Hydrosulphon Blue B 5% 3asic ... Methylene Blue 1 yo ... 1 4

... Pyrogene Indigo Greener 5%

fat (Anthr.) Chloranthrene Blue ED 2./,’ _.. 51 3irect

Sulphur

Basic Direct Sulphur

,,

Direct Diazo Basic Direct

__-

... Direct Green B 1%... . . . . . . I &

... Dianol Green BW 1% . . . . . . 14

... . . . . . . 14 Chlorazol Green 1 yo

... Thionol Green O Y 5% ...

... Thionol Dark Green 5%

... Pyrogene Dark Green B 5 yo ... lt ... Pyrogene Green G 5%

... Malachite Green 1% Pyrogene Green 3G 5%

... Thional Brown G 5% Trisulphon Brown 2 6 1 yo..

... Pyrogene Brown CX new 5%

... Pyrogene Cutch 2G 5%

... Thionol Brown P 50/

... Thionol Brown 0 59; ... Thionol Khaki 1 5%

... Thionol Corinth OX 5% ... Barking Sulphur Brown B 5%

... Khaki Brown C 5%

... Sulphol Yellow Olive G 50;;;‘ ... 14 ... Sulphol Yellow Olive 5G 5%

... Sulphol Brown JR 5% . . . . . . 4 ... Hydrosulphon Brown B 5%

... Cross Dye Deep Brown R 6 */o

... Trisulphon Violet B 1% . . . . . . 4 .

... Rosanthrene Violet 5R 3%

... Methyl Violet 2B 1% on 2% m o d .

... Dianol Black 1 3% Aniline Black. various eamples

”. ;i

. . . . . . “. ?

. . . . . . ’.. :+

. . . . . .

. . . . . . 3 ... ...

... . ... 2

. . . . . . 3

. . . . . . 14

. . . . . . 24

. . . . . . 1s

. . . . . . 3 ... 5 ... 5

... 1

... 1 ... 2

... 1

. . . . . . 14 ... 3-6

-

On receipt of a copy of the report of the Zommittee of Adjudication, which will be found x i p. 184, the author of the paper wrote as under :-

“ I have now standardised more than 140 zolours by this method, and while I have found it useful, especially for comparing the fastness of a sample colour with that in use at the time, I have myself found it not always easy to determine the exact point a t which the Eosine test paper should be removed. This is especially the case througk the dark weather of autumn and winter, when the pink colour fades very gradually, and if a unit-cobw giving a sharper end-point could be found, the method would undoubtedly be more valuable. The difficulty of findinga suitable colour is, of course, increased by the consideratioh that while i t should be as fugitive to light as possible, it must bc fast t,o acid and alkali, so as to remain nnaffected by ammonia, acid fumes, &c., in the atmosphere. The Eosine test papers have, in my experience,

The paper is admittedly incomplete in detail, but the publication of the method may induce others to work along the same lines in the hope of discovering a more satisfactary unit-colour.”

Yours faithfully,

fulfilled the latter reqiiirement fairly well. . . .

ALICE ROBSON.