I'm looking at purchasing some silk knit yard goods that contain 6% lycra. What kind of dye is required to color lycra, and is the fiber easily damaged by high heat?

Lycra is supposed to be easily damaged by high heat. I have not been able to find out exactly how *much* heat. Industrially, it is dyed at 160°F, using acid dyes, but applying this much heat to a ready-made garment would probably be a mistake, because apparently the fibers are set with heat. The garment might become misshapen if dyed this hot. All garment washing instructions for spandex-containing garments  call for the use of cool water, generally not to exceed a temperature of 105°F. I'm not sure whether yardage would be less of a problem than readymade garments. My choice for dyeing lycra/silk garments would be a cool water fiber reactive dye such as Procion MX or Cibacron F, used with soda ash just as for dyeing cotton or rayon, because I want to avoid having to use heat at all. The lycra itself will not be dyed, but for fabrics containing no more than, say, 12% spandex, with the balance being a natural fiber, usually dye very acceptably even though the spandex threads remain white. The lycra usually does not show at all except when the fabric is stretched.

Here is a link to a page that I wrote a couple of months ago about spandex:
http://www.pburch.net/dyeing/FAQ/spandex.shtml
This is the first time I've published the link.

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