|The urine vat was much used in the past for small-scale dyeing until ammonia became available from coal tar distillation early in the 19th century and other chemical methods were developed.
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The urine vat
To DYE INDIGO BLUE. Urine Vat.-
Prepare vat as follows : To 3½ gallons of stale urine add 4½ oz. of common salt, and heat the mixture to 125º F. (as hot as the hand can bear). Keep at this heat for 4 to 5 hours, frequently stirring, then add 1¼ oz. thoroughly ground Indigo and 1¼ oz. Madder, stir well and allow to ferment till the Indigo is reduced. This is recognized by the appearance of the vat, which should be of a greenish yellow colour, with streaks of blue. Allow the vat to settle, when you can proceed with dyeing.
Mairet E M, Vegetable dyes, being a book of recipes and other information useful to the dyer (1st edition, 1916), p. 72.
Receipt 123d. The Cold Vat with Urine.
A VAT is also prepared with urine, which yields its colour cold, and is worked cold : for this purpose four pounds of indigo are powdered, which is to be digested on warm ashes twenty-four hours, in four quarts of vinegar ; if it is not then well dissolved, it must be ground again with the liquor, and urine is to be added little by little, with half a pound of madder, which must be well diluted by stirring the liquor with a stick ; when this preparation is made, it is poured into a vessel filled with 63 gallons of urine ; it matters not whether it be fresh or stale ; the whole is well stirred and raked together night and morning for eight days, or till the vat appears green at the surface when raked, or that she makes flurry as the common vat ; she is then fit to work, without more trouble than previously raking her two or three hours before. This kind of vat is extremely convenient, for when once set to work, she remains good till she be entirely drawn, that is till the indigo has given all its colour ; thus she may be worked at all times, whereas the common vat must be prepared the day before.
This vat may at pleasure be made more or less considerable by augmenting or diminishing the ingredients in proportion to the indigo intended to be made use of; so that to each pound of indigo add a quart of vinegar, two ounces of madder, 15 or 18 gallons of urine. This vat comes sooner to work in summer that in winter, and may be brought sooner to work by warming some of the liquor without boiling, and returning it into the vat ; this process is so simple that it is almost impossible to fail.
When the indigo is quite spent, and gives no more dye, the vat may be charged again without setting a new one. For this purpose, indigo must be dissolved in vinegar, adding madder in proportion to the indigo, pouring the whole into the vat, and raking her night and morning, and evening as at first, she will be as good as before; however she must not be charged this way above four or five times, for the ground of the madder and indigo would dull the liquor, and in consequence render the colour less bright. I did not try this method, and therefore do not answer for the success ; but here follows another with urine which gives a very lasting blue, and which I prepared.
Bemiss E, The dyer's companion, in two parts. Part first, containing a general plan of dying wool and woollen, cotten and linen cloths, yarn and thread. Also, directions for milling and finishing, stamping and bleaching cloths. Part second, contains many useful receipts on dying, staining, painting, &c (1815) New York : Evert Duyckinck, pp. 154-155
Urine bath according to Cajsa Warg, 1762
Take urine, preferably of those who drink strong drinks, put it into a firkin, or jug that has a lid with cloth between, so that it is kept well stopped, and allow it to stand in a warm, but not hot oven, for 3 to 4 days; then the clear is poured off, but the thick is thrown away and the firkin is rinsed clean, then the clear is poured back in. The indigo is pounded quite fine in a . . . bag made of thin linen. . . which is placed in the clear urine, where it is left for 4 to 5 days, but rubbed once a day, after which a bit of woollen yarn is put in to test the colour. If the wool is green when it has lain there half a day, the dye is good: then, first, each skein is dipped in it, the one after the other, and wrung out; then they are all thoroughly shaken out and laid quite flat in the firkin. When they have lain there from morning until noon, they are again wrung out and put back again as they were after being thoroughly shaken out. Thus they must lie 2 or 3 days, till they become as dark as is wanted, then the dye is wrung out of it. . . the yarn is then washed and then rinsed. . . then it can be hung up and dried.
Sandberg G, Indigo Textiles, Technique and History (1989) Lark Books, p. 171.
The Indigo Vat with Urine according to Homassel
This is set variously: some prepare the urine in a boiler, before they turn it into the cask; others leave it to ferment by itself at leisure in the cask appropriated for a vat. They then take the clear part, and heat it without boiling, and scum it. Four ounces of good indigo are used to a pipe (tonne:) and as much alum as indigo. It is well stirred and covered, the door of the fire-place shut, and so left till next day, when it ought to put on the green colour. If it has not come to, by this time, put in a wine glass full of brandy and as much vinegar mixed together, which operates as a ferment, and brings on the liquor in seven or eight hours. When it is in order, it is left to rest, and used when it is wanted. When once in order, it continues so, and improves by keeping; the only difficulty is to bring it once into order, and it is valued for its age. When this urine vat is used, it is well warmed, and charged with indigo and alum, in the proportion of a pound of each to every thirty pounds of wool to be dyed. It should not be employed till twenty-four hours after it is in order; the wool is plunged in and worked under the liquor, and left there for an hour, the vat being covered; this is done as often as the required shade of colour calls for it. The vat should not be altered, but always left to rest, and to grow cold in its original state.
In country places, the girls dye blue thus: they fill a large earthen pot with scummed urine, in which they put an ounce of indigo and an ounce of alum; this mixture is heated on hot embers at first, and warmed whenever it is to be used. The wool is previously well scoured, and freed from its grease, by means of a weak ley of fresh wood ashes.
Homassel, citoyen, Cours théorique et pratique sur l'art de la teinture ... suivi de l'art du teinturier-dégraisseur et du blanchisseur, avec les expériences faites sur les végétaux colorans, (1807), Paris : Courcier. p. 176
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