By Liz White, UT staffDormagen, Germany-Dorlastan Fibers GmbH has added a new grade os spandex stretch fbre, Dorlastan Black, to its range. The firm says this new grade prevents unacceptable show-through in dark fabrics-regardless of which other fibres they contain. Dormagen-based Dorlastan says this new product means separate overdyeing of the spandex fibre is unnecessary. Dorlastan Black also prevents grin-through in elastic combination yarns containing dark dyed hard fibres such as polyester, polyamide or acrylics.Dorlastan Black-a polyester-based fibre type available in 40 and 70 denier-has excellent fastness to light, UV and oxides of notrogen, its manufacturer says. And since it also has "outstanding stability to PER and chlorine, it is suitable for use in swimwear (see picture) and can be dry cleaned without problem," the company said. Its black colour is stable to cleaning with both solvents and aqueous liquids.Dorlastan's products are filament yarns made of segmented polyester/polyurea urethane. The yarn-used in small amounts to give fabrics optimal stretch properties, dimensional stability and wear comfort-can be used as bare or covered yarns in virtually all textile applications, its maker claims. It is suitable for use with all natural fibres and with manmade ones such as polyamide, polyester, acrylic and acetate."