The Dyer's Guide. Chapter VI. On Dyeing Cotton And Silk. On dyeing silk of a Prussian blue colour.

The Dyer's Guide
Being a Compendium of the Art of Dyeing
Linen, Cotton, Silk, Wool, Muslin, Dresses, Furniture, &c. &c.

With The Method of
Scouring Wool, Bleaching Cotton, &c.
Directions for Ungumming Silk, And For Whitening And Sulphuring Silk And Wool.
And Also
An Inttroductory Epitome of The Leading Facts in Chemistry, As Connected With The Art of Dyeing.

By Thomas Packer,
Dyer and Practical Chemist.

"Cet arte est un des plus utiles et des plus merveilleux qu'on connoisse."
- Chaptal.

"There is no art which depends so much on chemistry as dyeing."
- Garnett.

Second Edition,
Corrected and Materially Improved.

Printed for Sherwood, Gilbert, And Piper,

The application of colours derived from the mineral kingdom to dyeing is one of the most striking modern improvements in our art. Mr. Raymond received from the French government in 1801, eight thousand francs, (more than three hundred pounds sterling,) as a reward for communicating to the public his process for dyeing silk of a uniform fast and bright Prussian-blue colour by the application of that well known pigment. His process is as follows.

He first converts, by a gentle calcination, sulphate of iron into a red sulphate of iron: this he dissolves in sixteen times its weight of warm water and filters. The silk, prepared as for indigo dye, is put into the solution of iron, and left there for a shorter or longer time, according to the shade of blue that is wanted; it is then taken out and wrung very dry over a pole placed above the vat. It is then thoroughly cleansed by being twice beetled, plunging and agitating it each time in. running water. Dissolve in pure water heated to 167°, and put into a deal vat, one ounce oi ferroprussiate of potash, for every twelve ounces of silk to be dyed. When the prussiate is dissolved add one part, or even rather more, of muriatic acid, stirring the mixture well. When the liquor has acquired a greenish colour, and about 144° of heat, the silk must be immediately plunged into it and stirred about for some minutes. The silk having received the dye in an equal manner, it is taken out of the vat, well wrung on a pole above the vat, and then taken to the stream to receive two or three beetlings, and be plunged and agitated in the water, in order that it may be entirely freed from any portion of the prussiate of iron not truly combined with it.

Lastly, the silk being well washed in the stream, and thoroughly wrung, is to be placed loosely on the poles, as in the preceding operations; after which it must be well agitated in a large vessel three-fourths filled with cold water, to which must be added, for a hundred pounds of silk, two pounds of water of ammonia. The blue colour immediately becomes many shades deeper, of a much richer and brighter tint, and at the same time is fixed more perfectly in the silks. This change is effected in a few minutes. The silk must then be wrung by the hand and rinsed in the running water without beating. After this, it is dried on the poles in the same manner as other dyed silks. It need not be left on the poles more than twenty-four hours: but, nevertheless, this colour so far from fading in the drying, as is the case with many colours, is improved by it.

The solution of a little soap added cold to the ammonia bath, improves it, giving also softness to the silk, and rendering it more easy to separate. The soap should be uniformly dissolved.

For the substance of the above process, we are indebted to Dr. Ure's notes on Berthollet, vol. ii. p. 422. The prussiate of potash is now to be obtained as a regular article of trade from the dry-salters in this country.

Woollen cloth takes also the above dye, but it must be left longer than silk in the iron mordant.

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