Direct dyes stripping

It can be prepared either by using appropriate direct dyes or reactive dyes. In the latter case, pure linters (the raw material for high-quality paper) are suspended in water, and the solution of the reactive dye is added. For example, the dye 15 reacts via the sulfonic acid group in the side chain. The reaction mixture is then made alkaline and the dye reacts with the linters. After completion of the reaction, the fiber pulp is centrifuged, washed electrolyte-free, and processed on a paper machine to form the pH paper. Paper produced in this way is mostly bonded onto a plastic material and used as pH test strip. 

Tests for Identification of Some Synthetic Dyes. Two very simple reactions can confirm the presence of synthetic dyes. In the solvent stripping test, if the ammonia solution is heavily stained and it becomes irreversibly colorless upon the addition of zinc dust even at room temperature, the presence of an azo dye with sulfo group or groups is indicated (an acid or direct dye) (36, 37). The color of the solution in concentrated sulfuric acid can also be an important indication for identifying synthetic dyes. In this test, a few drops of concentrated sulfuric acid are dripped on a small sample of the dyeing, and the color of the sulfuric acid is observed after a few minutes. Intensive magenta red, red-violet, violet, blue, and green solutions indicate the presence of synthetic dyes (36, 37). 

Excellent stripping agent for vat, sulphur and direct dyes. Also used when washing off vat, reactive or acid dye prints to prevent staining of white or pale ground. 

OrcogalST. [Organic Dyestuff] Stripping assistant fm vat, sulfur, aiiid direct dyes dispersant in soaping prints. 

Uses Reducing agent for reduction clearing and stripping of polyester and disperse dyes or for stripping of direct dyes cleans dyeing machinery of dyestuff and Irimer buildups in conjunction with alkali... 

Uses Dispersant, dye solubilizer, soaping off agent for reactive, direct, and disperse dyeing chelating agent for dyebath without demetalizing dyes Features Nonfoaming multifunctional increases the salt tolerance of carriers and disperse dyes increases the solubility of reactive and direct dyes does not strip metal from metal complex dyes... 

Stripping test for acid colours. Some direct or " salt dyestuffs are partly decolorised by dilute ammonia and hence might be regarded as add colouring matters. To avoid this error it is useful to add, when this test is made, a piece of mercerised white cotton. With an add dye, the cotton remains white, or is scarcely coloured, and then becomes white again when boiled a second time with dilute ammonia. 

After staining, the amounts of dye taken up by the various fractions may be determined either by scanning the strip directly or by photometry of the eluted fractions. In the first method the paper acts as a source of error which is difficult to eliminate effectively, whether the paper is rendered translucent and the transmitted light is measured or whether it is untreated and the quantity of reflected light is measured. In the second method the cutting up of the paper to separate the fractions must be followed by perfect elution without influence on the color of the dye, but subsequent photometry is easy. 

Best possible leveling properties under HT dyeing conditions. Very well suited as repair or (in higher concentrations) as stripping carrier. Easy to emulsify. Provides very stable emulsions even when poured directly into the dye bath. Requires only low concentrations. 

Vat Stripping CNC LEVELER 45 retards the dyeing rate of vat colors in direct proportion to the concentration used. 

Start about 1 cm away from where you applied the sample in the opposite direction from where the dye moved. Lay the sharp edge of the microscope slide on the gel and, with one swipe, scrape away the excess. Do the same to the other side of the strip about 1 cm beyond where the marker dye is. 

A schematic of a test strip is shown in Fig. 5.12. The adsorbent material is usually enclosed within a plastic casing featuring a sample input window, a test result window and a control window. A drop of urine is applied at the sample input and the liquid first moves over the zone, which contains the labelled tracer antibody (Fig. 5.13). If hCG is present in the sample, it forms a complex with the tracer antibody. This complex continues to move along the adsorbent material and passes over the area with the immobilised capture antibody. A sandwich is formed between the immobilised capture antibody and the tracer antibody with the hCG in between. Thus, the initially mobile antibody with the label becomes immobilised. The amount of sandwich complexes formed is directly proportional to the amount of hCG present in the sample. If the hCG concentration exceeds a minimum concentration, the dye colour becomes visible to the eye. 

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