Just wait until you start desynthing them. Even at 100 desynth skill you only have 70% success rate. Also even when you do succeed the chance of it dropping is low. All that rng hell just to get a vanity piece. I really don't know what SE was thinking when they decided to make this material incredible hard to obtain unless you're an rng god. I quit trying to get the waterproof cotton after I successfully desynthed 10 olgois and the best thing I got out of it was clear demimateria III. I could live with all the rng if they only made it a 70-100% drop after a successful desynth but that's not even the case. It's kinda sad that a piece of vanity is the hardest piece of clothing to obtain in the game. Even clearing turn 9 is a more reachable goal for most players than getting this piece of cotton. I wish luck to the rest you going after this material because you're going to need alot of it.