Receipt for an Ash Vat for Dyeing Indigo Blue.

Scientific American 15, 1.1.1848

Fill the vat with clean water; then put fire to heat it and put the dyestuffs in at once, as follows: To one pound of indigo allow three pounds of the best pearl ashes, and 8 ounces of madder to every pound of indigo; after they are all in stirr well up with a rake; when that is done cover the vat up with cloth that no air may get in. The bran should be put into a bag, because if the vat does not spring there arises a putrid smell. The only thing to remedy that is to give the vat a little quick lime, but be careful not to put too much in as for fear of what is called softening the vat; also care must be taken not to overheat but keep only at good heat, because if the vat is overheated the indigo will lose the combination with the ashes and adder and the vat will turn muddy in the color. The remedy for that is 1 lb. of pearl ashes with 4 ounce of madder. If it does not spring and come to a working state in 12 hours, then add a little bran in a bag with half a pound of ashes; if it foes not spring with that in 12 hours take out the bran and put in about two quarts of malt with one pound of pearl ashes and four ounces of madder, with a little lime.

A very fast blue with indigo is dyed by saturating powdered indigo for some days, kept at a fermenting heat in a vessel filled with urine and which is better of a little bran and madder. No faster, or more primitime blue onwool is dyed than in this manner, and any person can do it.

The receipt for an ash vat can only be useful to manufactories. The ash vat is used for dyeing a fast blue on silk, such as a basis for a green colored umbrella to stand exposure to the sun. All our common blues and greens on silk are very fugitive, with the exception of Prussian blue, which we shall treat of at another time.

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