This is what the yarn says about itself in its Ravelry thing:
Theseus Lace is named after the mythical founder-king of Athens. Strong and hardwearing, the merino is superwash treated (not that you should be machine washing your lace!) and the silk lends heaps of extra strength. It is superbly glossy, smooth and soft.
The Rav projects seem to be mostly shawls. No one would toss a lace shawl in the washing machine anyway.
It sure is beautiful yarn, I'll say that!
If I was knitting socks with this yarn...I would hand wash them. Just sayin....