To Dye Blue.

Scientific American 14, 25.12.1847

For the Scientific American.

A light blue may be dyed on silk by the sulphate of indigo, that is, 1 pound of the best indigo ground fine to 6 pounds of pure sulphuric acid, added gradually and stirred well. It will take three days tomake well, and nine perfectly. It is good to keep the vessel in which the chemic, as it is called, is made, at a moderate heat in cold weather. A very small portion of this compound mixed well with warm water, will dye a very good blue on silk, and if turmeric or fustic are added to the chemic solution a green is the result. This mixture will also dye blue on woollen but the goods must be boiled in it, and if a dark shade is wanted, a preparation of the goods in logwood liquor having a small quantity of the muriate of tin along with it, is a good basis - then the indigo sulphate on the top. It is impossible to describe the exact quantities, more or less of each is given according to the shade wated. The sulphate of indigo will not dye cotton unless the acid is neutralized by feeding the chemic with chalk. A beautiful pencil blue is made by adding the acetate of lead to the sulphate of indigo. This composition is used in calico printing.

A blue can be dyed on wool by boiling woollen goods for one hour in a preparation of the sulphate of copper, two ounces to the pound and a little alum, then wash them well and boil one hour longer in logwood liquor. This color is very fugitive. A more fast color may be made by using the same quantity of copperas and one ounce tartar to the pound of goods, and treating the goods in the same manner. Boiling don't spoil woollen goods as some suppose, for all colors on wool, are boiled and the better they are boiled the faster and cleaner the colors will be. By increasing the quantity in the last receipt a good blue black is the result.

A logwood blue can be dyed on cotton by a preparation of the cotton for two hours in a strong solution of the sulphate of copper and alum, then washing them well, squeezing or wringing them and afterwards putting them through a good strong solution of logwood and then running them through a weak solution of soda ley. There are very few colors that are dyed on cotton that have to be boiled, in no instance is it necessary for logwood colors to be so treated. This color will do well for carpet rags and coarse canvas that may be used to tread upon, such as to cover stair carpet. Blue can also be dyed upon cotton by repeated dips in a strong solution of the sulphate of copper in one vessel and caustic potass in another. The goods must be wrung out of each of the solutions. This is an expensive color and cannot be done easily, but it is the most perfect sea blue of all the blues, and if arsenic be added to the copper solution, it make the beautiful sea, or sage green. Like the serpent, it is beautiful to look upon but it is as dangerous to the labor at, as to receive the bite of the reptile. Many a dyer has lost his life by this color.

We have been very plain, so that any person may understand the meaning of foregoing receipts. We shall treat of the dyeing of indigo blue on cotton, silk and wool, in our next.

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