My understanding was that there are three types of rayon. Or have I been had by Big Cellulose?

• Viscose is the one that gets weaker when wet, and uses aggressive chemicals
• Modal gets stronger when wet, but also aggressive chemicals
• Tencel (brand name for lyocell) specifically refers to that closed loop process with less harsh solvents, and also gets stronger when wet

If something just says “Rayon” you can probably assume it’s viscose. Tencel sellers want you to know it’s Tencel.

Regardless, none of the above are good for warmth, so bad replacement for wool no matter which process they use. I do love my Tencel bedsheets though.