Scientific American 17, 7(?).1.1855
In the last number we described the method of dyeing cotton yellow with the bi-chromate of potash and the acetate of lead. The salt formed in the cotton which makes this dye (reflects the yellow ray of light,) is temed the "chromate of lead." Chrome colors are more permanent that any known vegetable yellow colors, because the metal chromium, which is the base of the color, is not easily oxydized.
Bark Yellow
A very good yellow can be produced on cotton by Americal yellow oak bark (Quercitron,) by the use of the sulphomuriate of tin as a mordant. About five pounds of barks will dye a good full color on ten pounds of cotton yarn. The bark is placed in a bath of boiling water and suffered to boil about ten minutes, then about one-sixth of a pint of spirits (nitro-muriate of tin,) is added for every ten lbs. of yarn; the liquor is cooled down about ten degrees, and the yarn entered. It is handled (turned over pins) in this for about fifteen minutes, and then lifted to drip, taken out and aired. It is best not to give all the dye stuff at one dip, but at two or three separate dips, as the airing and dripping after each dip seems to give the yarn an appetite (to use a common term) to eat up the dye stuff more cleanly, and produce a deeper shade from the same quantity of dye wood.
Yellow on Wool
This bark is used to dye yellow on wool and flannel, which must be boiled in the liquor, otherwise the process is the same as in dyeing the cotton. The yellow oak bark must be placed in a clean bag to prevent it sticking like burrs to the goods. Dr. Bancroft, of London, discovered the qualities of this bark as a dye while on a visit to the Colonies, before the Revolution. It makes a very good and beautiful yellow. Fustic, another dye wood, makes a tolerable yellow, by using a mordant of alum. It is but seldom used now, however.
Yellow on Silk.
A fugitive yellow is dyed on silk with turmeric. This dye wood is scalded in a clean vessel with boiling water, and the clear poured off into the dye kettle, and then a little sulphuric acid added (about enough to give a sharp sour taste to the liquor.) The silk is then entered and well handled for fifteen minutes, when it will assume a fine yellow color, capable of standing the action of an acid, but fades away very fast when exposed to the rays of the sun. One pound will dye five pounds of silk. To dye silk with fustic, the goods are steeped for two hours in a strong solution of alum, then taken out and entered in the fustic liquor, in which they are handled for about half an hour. It takes about ten pounds of fustic to dye ten pounds of silk, or twenty pounds of wool a tolerable yellow. The wool in the state of yarn, and also the silk, are handled like cotton, on pins, but the wool is only dripped, never wrung; the cotton and silk yarn are wrung and not boiled, but the wool is always boiled in the liquor. The weld plant was at one time extensively used in dyeing in France and England, but never in America. The bi-chromate of potash, yellow oak bark, fustic, and turmeric, are the dye stuffs generally used for dyeing yellow on cotton, silk, and wool, in our country.
Wool must be scoured from its grease before it will absorb the dye from the liquor, and for this purpose good soap is the best substance, but the quantity is economised by the used of soda lye, which converts the grease of this wool into soap, which can be easily washed away with water. A dye shop should always be located on a stream of solft water, because hard water adds greatly to the expence in neutralizing the useful effect of the soap used in scouring.
Silk must be prepared for dyeing - that is raw silk - by boiling it in good soap until all the natural gum is removed from it. Notrhing has been discovered equal to good soap from removing the gum from silk. The soap is cut up in small pieces and dissolved in water in a clean boiler, until it has attained to a strength that will feel slippery between the fingers; into this the silk is entered; if in hanks, it is turned on pins; if in pieces, it is reeled over a "winch," or if in dresses (like old silks dyed by renovating dyers,) it is dropped loosely into the boiler and turned with a clean wooden smooth stick. Most persons will be liable to conclude that boiling silk in strong soap suds would destroy its texture, but it is a fact, that all silk must be boiled in soap before it can be dyed. All the soap must be well washed out before the goods are ready for dyeing, and after goods are dyed they should also be well washed.
Cleanliness is one great secret of success in a good dyer. Spun silk is merely scalded in hot water, and is then fit for the dye tub. Cotton and silk in pieces are selvedged, drawn constantly between the hands by the selvedges, from end to end of the piece then plunged under the liquor, until they are finished in the dye, or else they are turned over a winch or reel. Woolen goods in pieces, such as broad cloths, merino twills for ladies wear, and such kinds of goods, are all handled on reels in both the mordant and dye kettles.
Alum is the common mordant for silk; a tub of it in solution about 3° in Twaddle's hydrometer, or of a very strong taste (a practical dyer can tell the proper strength by tasting,) is always kept ready in every dye shop.
By the old method of dyeing wool, in yarn or in piece, all the goods were first mordanted before they were boiled in the dye wood. The modern system is to use the mordant and dye stuff in one kettle for most colors, and dye off at one operation; thus shortening the process. (This we shall describe for each color.)
The "spirits" in general use for dyeing is the nitro-muriate of tin. Some dyers use a great variety of such spirits, but it is all nonsense. One kind will answer for every color, as well as to have fifty of different proportions. These spirits are made by taking nitric and muriatic acids, one part, by measure, of the former to seven of the latter, and feeding in pure tin, in small pieces, very slowly, until the acid will not dissolve any more. It is best to take three days to make these spirits. The muriate of tin will answer, its own self, every purpose of a jobbing or renovating dyer, and as it is more easily kept and made, no other should be used in our climate.
Saffron is employed for making yellow ink, and a new vegetable substance named "wongshy," a nativa of Batavia, has lately been introduced into Germany with some success, to dye yellow on cotton and wool, but it is more expensive for this purpose than chrome and yellow oak bark.
Within the past thirty years, the chrome has almost entirely superseded vegetable substances for dyeing yellow on cotton. It is an oxyd of the metal chromium (Cr., chemical symbol,) which is found combined with iron (chrome iron,) which it its principal ore, in Maryland. The composition of this ore is Fe.O.+Cr.2O.3. The pure metal is unknown in the arts, only known in the laboratory. Some other substances are employed for dyeing yellow, but as they cannot be used, owing to their great expense, in the arts, it would be imprudent to occupy space in describing the methods of using them.
By the plan we have described for dyeing yellow on wool, every person can dye their own family flannel yellow with great ease, in a clean tin kettle.
This completes all we have to say on dyeing yellow, one of the primary colors. Our next article will treat of the various plans and substances for dyeing red.
Ei kommentteja :
Lähetä kommentti