As we are considered as one of the largest manufacturer, supplier and exporter of direct dyes, we are too sensible for the offered quality of our product. Every shipment is dispatched only after stringent testing of the quality on varied international parameters and also on the parameters set by industry. First of all it is tested for strength. It is tested against standard system.
Each shipment is also checked for spectrum by comparing it with standard spectrum. The mixture of the dyes is also tested with strict compliance. We also provide certificates of analysis (COAs).
Direct dyes are used on cellulose fibers such as cotton, rayon, and linen. They lack the permanence of the cold water fiber Paper Dyes which most serious dyers prefer for use on cellulose fibers, but in some cases they have advantages that make their use worthwhile. For example, while many of the direct dyes are not very lightfast, there are some dyes in the class that may be more lightfast than similar shades of fiber Paper Dyes.
All direct dyes perform rather poorly with respect to washfastness. Without an appropriate after-treatment, direct dyes bleed a little with every washing, losing their brightness and endangering other clothes washed in the same load. However, there are special after-treatments which may be used to solve this problem. (Vinegar is not among them! In spite of claims you may see to the contrary, you cannot use vinegar to set any dye on cotton or other cellulose materials.) A product called Retayne, which is an ionic bulking agent which essentially "glues" the dye into the fiber, works very well to make fabric dyed with direct dyes washable without bleeding of the dye.