TLDR; they reprocess natural silk from silkworms to produce silk fibers with better tensile strength. This is partly achieved by doing a better job of washing o

TLDR; they reprocess natural silk from silkworms to produce silk fibers with better tensile strength. This is partly achieved by doing a better job of washing out non-strong compounds from the fiber, so the yield is strictly lower than that for natural silk. This process still involves boiling silkworms alive. This contrasts from biotech based fibers, e.g. https://boltthreads.com/technology/microsilk/ https://boltthreads.com/technology/microsilk/ , which is produced by genetically modified yeast.