The silk should be boiled at the rate of 20 parts of soap per cent., and then alumed. The aluming need not be so strong as for the fine crimson. The silk is refreshed at the river, and passed through a bath more or less charged with Brazil juice, according to the shade to be given. When water free from earthy salts is employed, the colour is too red to imitate crimson; this quality is given it by passing the silk through a slight alkaline solution, or by adding a little alkali to the bath. It might, indeed, be washed in a hard water till it had taken the desired shade.
To make deeper false crimsons of a dark red, juice of logwood is put into the Brazil bath after the silk has been impregnated with it. A little alkali may be added, according to the shade that is wanted.
To imitate poppy or flame colour, an annotto ground is given to the silk, deeper even than when it is dyed with carthamus. It is washed, alumed, and dyed with juice of Brazil, to which a little soap water is usually added.
The colouring particles of Brazil wood are easily affected, and made yellow by the action of acids.
They thus become permanent colours. But what distinguishes them from madder and kermes, and approximates them to cochineal, is their reappearing in their natural colour, when they are thrown down in a state of combination with alumina, or with oxide of tin. These two combinations seem to be the fittest for rendering them durable. It is requisite, therefore, to inquire what circumstances are best calculated to promote the formation of these combinations, according to the nature of the stuff.
The astringent principle, likewise, seems to contribute to the permanence of the colouring matter of Brazil wood; but it deepens its hue, and can only be employed for light shades.
The colouring particles of Brazil wood are very sensible to the action of alkalies which give them a purple hue; and there are several processes in which the alkalies, either fixed or volatile, are used for forming violets and purples. But the colours obtained by these methods, which may be easily varied according to the purpose, are perishable, and possess but a transient bloom. The alkalies appear not to injure the colours derived from madder, but they accelerate the destruction of most other colours.
In England and Holland the dye-woods are reduced to powder by means of mills erected for the purpose.
The bright fugitive red, called fancy red, is given to cotton by Nicaragua, or peachwood, a cheap kind of Brazil wood.
The cotton being scoured and bleached, is boiled with sumach. It is then impregnated with a solution of tin (at 5° Baumé, according to Vitalis). It should now be washed slightly in a weak bath of the dyeing wood, and lastly, worked in a somewhat stale infusion of the peach or Brazil wood. When the temperature of this is lukewarm, the dye is said to take better. Sometimes two successive immersions in the bath are given. It is now wrung out, aired, washed in water, and dried.