Dictionarium Polygraphicum. Bleaching, blanching.

Dictionarium Polygraphicum:
Or, The Whole Body of Arts Regularly Digested.
Vol I.
London: Printed for C. Hitch and C. Davis in Pater-noster Row, and S. Austen in St. Paul's Church Yard. MDCCXXXV.
1735 BLEACHING, BLANCHING, is the art or method of whitening linens, s stuffs, silks, &c. and is as follows.

For Bleaching fine linens.
When they come from the loom, and while they are yet raw, they are to be steep’d a day in clear water, wash'd out and clear'd of their filth, and then thrown into the bucking tub, fill'd with a cold lixivium or lye.
When these are taken out of the lie, they are to be wash'd in fair water, then spread in a meadow, frequently watered from little dikes or canals interspers'd in the ground, by means of scoops or a sort of long hollow shovels, call'd by the Dutch, who invented them, gieter.
After the linen has lain a certain time on the ground, and every thing has been repeated as before, it is to be pass'd thro' a new lie pour’d on hot, and again wash’d in clear water, and laid a second time on the ground; and then pass'd thro' a soft gentle lie, to dispose it to resume the softness, which the other sharper lies had taken from it, then wash’d in clear water, soap'd with black soap, and that soap is to be wash'd out again in clear water; then it is to be steep'd in cows milk, the cream having been first skimm'd off, which finishes the whitening; and scowring gives it a softness and makes it cast a little nap; when it is taken out of the mill, it is wash’d in clear water for the time.
After all this process, they give the linen its first blue by passing it through a water, wherein a little starch, pale, smalt, and Dutch lapis have been steep'd. In the last place, the proper stiffness and lustre is given with starch, pale, smalt and other gums, the quantity and quality of which may be adjusted according to occasion. The whole process of Bleaching is finish’d in fine weather in a month's time; in ill weather, it takes up six weeks or more.

To BLEACH coarse linens, they are taken from the loom and laid in wooden frames, full of cold water, where they are so beaten by wooden hammers work'd by a water-mill, as to be insensibly wash'd and purg’d from their filth; then they are to be spread upon the ground in order to receive the dew foreight days, which will take off more of the rawness: then they are to be put into a kind of wooden tubs or pans, with hotlye pour’d over them.
Having been thus lixiviated, they are again purg'd in the mill, then laid on the ground again for eight days more, then they are to be pass'd through a second lye; and all things repeated, till such time as they have acquir'd their just degree of whiteness.

BLEACHING woollen stuff.
There are three manners of whitening woollen stuffs; the first is with water and soap, the second is with vapour of sulphur, the third with chalk, indigo and vapour of sulphur.
For the first, when the stuffs are come from the fulling mill, they are to be put into soap'd water, pretty hot, and work'd afresh by force of arms over a bench, which finishes the whiten ing which the fulling mill had begun; in the last place, they are to be wash’d out in fair water and dried; this is call'd the natural way of Bleaching.
The second method is what is commonly call'd Bleaching by the flower, thus; the stuff is first wash’d in river water, and then put to dry on poles, and when it is half dry, spread out in a kind qf stove wherein sulphur is burnt, the vapour of which diffusing itself, sticks by little and little over all the stuffs, and gives it a ine whitening.
The third method is thus; after the stuffs have been wash'd, they are to be thrown into cold water, impregnated with chalk and indigo, in which they are well agitated; they are wash'd afresh in elder water, then half dried on poles, and then spread in a stove to receive the vapour of the sulphur, which finishes the Bleaching.
This method of Bleaching is agreeable enough to the fight, yet is not esteem'd the best method of Bleaching.
This is to be remembred, that when a stuff has once receiv'd the steam of sulphur, it will scarce receive any beautiful dye, except black and blue.

BLEACHING of silk.
The silk being yet raw, is put into a linen bag, and thrown into a vessel of boiling river water, in which soap has been dissolv’d, and thus boil'd for two or three hours; the bag being turn'd several times, taken out and beaten, then wash'd out in cold water, and wrung out slightly, and thrown into a vessel of cold water, mixt with soap and a little indigo.
The indigo gives it the bluish cast that is observable in white Silks.
When it has been taken out of the second vessel, it is wrung out, and all the water and soap squeez'd out, shook out to un twist and separate the threads, and hung up in the air in a kind of stove made on purpose, in which sulphur is burnt, the vapour of which gives the last degree of whiteness to the silk.

BLEACHING HAIR, is done by spreading the hair to be bleach'd upon the grass, after the same manner as linen, after it has been first wash'd out in a lixivious water.
This lye with the force of the sun and air brings the hair to so perfect a whiteness, that the most experienc'd person may be deceiv'd therein; there being scarce any way of detecting the artifice, but by boiling and drying it; which leaves the hair of the colour of a dead walnut tree leaf.
There is also a method of dying hair with bismuth, which renders white hair, which borders too much upon the yellow of a bright silver colour. This also may be prov’d by boiling; the bismuth not being able to stand it