Nikwax Wax Cotton Proof
Here's what other sites are saying:
Prolonging the life and water repellency of your cotton, heavy-duty canvas, or poly-cotton fabrics, Nikwax Cotton Proof is an easy to apply wash-in or paint-on treatment. This water based treatment is environmentally friendly, biodegradable, non-flammable, non hazardous, and contains no fluorocarbons. Applications can be used on wet fabric, inhibits rotting of canvas, and will not affect the cosmetic appearance. It works great on everything from barn coats and duffel bags to outdoor clothing and tents.
- Altrec Outdoors