The scientists found different dyes moved through silkworms' bodies differently. Some never made it into the worms' silk at all. Others colored the worms and their cocoons, but the color molecules settled mostly in the sticky protein the worms add to their cocoons. That sticky stuff gets washed away before the silk is turned into fabric. Only one dye, named "direct acid fast red," showed up in the final, washed silk threads. By the time it made it there, it was a pleasant, light pink.