Reserve technology
Reserve technique is called an indirect dyeing process , which is used for textiles and paper, among other things. The decoration is applied with hot wax or with various paste-like substances, whereby these substances prevent the absorption of color during dip dyeing and are then removed again. As a result, the original color is retained at the covered areas, as z. B. is the case with batik and textile blueprint .
In order to obtain white patterns on a colored background, the fabric is covered with reserves (protective, cover paper) before dyeing , which prevent the dye from being absorbed. As Reservagen can wax - resin - sebum - and paraffin mixtures , even emulsion-like liquids from tallow, palm oil and rubber slime apply. Or you can print copper vitriol or verdigris solution with pipe clay and rubber (white cardboard) and then color in the indig vat. The indigo blue is only fixed in the unprinted areas on the fiber, and after washing out, the pattern printed with the copper salt appears white. If you mix in the reserve stain for a dye, you can use the pattern after the fabric has passed the indigenous vat, e.g. B. dye in madder or Waubad (lapis print). White patterns on a colored background can also be obtained by etching or enlevage. The former act on the stains, the latter on the dye. The etching stains combine with the base of the stain and detach it from the fiber. Tartaric acid , citric acid , phosphoric acid , arsenic acid etc., also tin chloride and tin (II) chloride are suitable for this . They are printed sufficiently thick on the fabric, the latter is pickled on the padding machine and colored out. The pattern printed with the etching stain remains white. Etching stains are often combined with ordinary stains. One blocks z. B. iron stain on and then printed with a mixture of lemon juice and red stain to remove the iron stain in places and replace it with red stain. If you then print on pure etching stain, dry it and dye it in a madder bath, you get a white and red pattern on a purple background. The enlevage used for indigo is chromic acid or ferric chloride or a mixture of red blood liquor salt with caustic soda ( Mercer's liquid), for Turkish red chlorine . One prints z. B. the turquoise colored tissue with tartaric acid and then passed through a chlorine lime solution . The chlorine developing on the printed acidic areas destroys the red dye.
The enlevagen can also contain stain so that the discolored areas can be stained otherwise. Before application of the Enlevagen for Indigo is often used to produce blue characters on a white background the Fayencedruck . Ground indigo was printed with iron vitriol on the white fabric and, by alternately treating it with iron vitriol solution and lime water, the indigo blue was reduced to indigo white and the latter was dissolved in lime water. This solution penetrates into the fabric, and when exposed to the air, newly formed indigo blue then fixes on the fiber (faience blue, English, Chinese, porcelain blue). Similarly, the signs blue (Box, brush blue), whose generation is a very concentrated vat from Auripigment imprints and caustic soda with rubber thickened.
In Turkish red, white patterns are also produced by means of ribbon printing. The fabric is laid in 12 to 14 layers between two lead plates that have been drilled or cut through in many places corresponding to the pattern, the plates are pressed strongly against one another and then a chlorine lime solution acidified with sulfuric acid is allowed to seep through, which can only be found in the paths corresponding to the cutouts moved and destroyed the dye here. Finally, you wash out under the pressure. If, after washing, a solution of acetic acid lead oxide and then a solution of chromic acid potash seep through, the formation of chrome yellow results in yellow patterns on a red background.
The methods given apply initially to calico printing . The printing of canvas is usually limited to indigo blue colored cloths with light blue or white patterns or similar simple items using blue printing . Chalkboard and steam inks are mainly used in wool printing. The Golgas pressure is similar to the bandana pressure, only the wool is first stained and then placed between the perforated panels. Berill printing is used to create colored raised patterns on wool by hot printing on board colors thickened with starch and not removing the thickener. The silk printing is generally similar to the calico printing. You print on board colors, which you fix with steam, or you print different stains and color in the color broth. In mandarin printing, the indigo-dyed silk is printed with a reserve of resin and fat, then immersed in dilute nitric acid at 50 ° for 2-3 minutes and washed and boiled in a soap solution mixed with potash . The non-reserved areas are colored intensely yellow by the nitric acid.
Printing with tar paint occupies a special position . The thickened stain is printed on calico, attached and colored, or the stain is padded or mixed with the dye, thickened, the mixture is printed on, dried and steamed. Egg white, glue and casein preparations, glue, tannic acid glue, tannin , fatty oils, oleic and palmitic sulfuric acid, shellac solution, etc. are used as stains.
Another method is to precipitate the tar dye from its solution with tannic acid, dissolve the washed-out precipitate in acetic acid, alcohol or wood spirit, print the thickened solution onto the stained stuff, steam and wash. You can also pickle with caustic soda, print on a gum-thickened gall-apple decoction, steam, fix the pickle in a normal fixative bath and then color it in an acetic acid solution of the dye. Finally, there is a bath with acidified water or a soap or bran bath.
