Worked great on cotton.It worked great on a Carhartt 12oz cotton duck jacket,was able to completely soak it down with the Scotchguard.Water beads up on it and mild dirt wipes off clean. Not so good on an older Columbia 100% nylon shell water repellent jacket,that after many washings had lost it's repellency. With only a light spraying of Scothchguard it made a waxy white coating that I thought had ruined the jacket. Would not wash out in wash machine. It took an abusive hand washing with a lot of detergent to remove it.Jacket was OK. Now I use Atsco Silicone Waterguard on all my nylon water repellent jackets to make them stain and completely waterproof.