I feel like a shill because this is my second plug this month, but I have no commercial afflilations.
Look at NikWax products. They can be found on-line or at places like REI. They have cleaning products and waterproofing products. I was mine in tech wash and then either wash it again in a proofing product or spray it with their tent water proofing. A great way to clean it and get some weather resistance heading into winter.
It's worked great for me.
If my post starts sounding like a rant, please start again from the top and imagine John Malkovich as the narrator. www.troyonbass.com