Лако-красочные материалы — производство

When dyes are exposed to daylight or sunlight, they undergo a change and are discolored and bleached. The rate of this fading varies greatly with different dyes and with different depths of color. Thus, some dyes are extensively faded by exposure to sunlight for 1 day, or even for a few hours. Others show a […]

This beautiful yellow dye first appeared on the market in 1930. It consists of a yellow powder which dissolves easily in water to give a pure yellow solution. Materials dyed by it are characterized by an ex­tremely pure, almost dazzling, yellow color which cannot be matched by any other previously known yellow dye. The dyed […]

Benzo light grey BL consists mainly of a blue gray dye mixed with a small amount of an orange red brown dye and, in certain cases, with some direct deep black. The presence of a mixture is clearly evident when a little of the dry powder is dusted onto wet filter paper. The blue gray […]

Reduction with Hydrosulfite. The reprecipitated dye (30 grams) is dissolved in 250 cc. water containing enough soda to make the solution distinctly alkaline to litmus. Hydrosulfite is added in small portions to the boiling solution until it becomes colorless. An excess of hydrosulfite is to be avoided or sulfur may separate. The yellowish brown oil […]

These two dyes were recently added to the sample card of the acid — and milling fast Polar dyes of the J. R. Geigy A. G. firm. Since methods for preparing milling-fast azo dyes have not been patented by this firm for several years, it is assumed that the two Polar brilliant red dyes either […]

The determination of the constitution of an unknown commercial dye is one of the most interesting, but also one of the most difficult, tasks of the dye chemist. In the earlier days when only natural products were used, it was a relatively easy task, in many cases, to determine the origin of a product by […]

A good average sample of 3 to 5 grams of the paste is weighed out between two watch glasses and treated with exactly 5 grams of Mohr salt. The mixture is rinsed into a 200-cc. flask and heated for 30 minutes on a boiling water bath, after which 25 cc. concentrated hydrochloric acid is added. […]

1 gram of Zn dust is dissolved in a solution of 4 grams of sodium bi­chromate in 1 liter water, and 20 cc. 20 per cent sulfuric acid added with thorough stirring. A 250-cc. portion of this solution is diluted with 900 cc. water, and 150 cc. 20 per cent sulfuric acid and 100 cc. […]

1. H Acid Solution. 1 per cent in 5 per cent soda, is used to test for easily coupling diazo compounds in spot tests on filter paper. R salt, /З-naphthol, hydrocyanic acid, etc. can also be used for this purpose. 2. Resorcinol Solution. 1 per cent in 5 per cent soda is used to test […]

1. Litmus Paper. This is an indicator for all acids and bases, weak or strong. Acids turn it red, bases blue. In preparing litmus. paper, only the best litmus is used. The cubes, which contain from 50 to 90 per cent of gypsum, are broken up and extracted once with alcohol. The dye is then […]