Under most circumstances all you need to do to keep your canvas tip top shape and clean is to regularly hose it down after a day’s outing. The heavy-duty cleaning won’t need to happen as often if you keep hosing it down.
Once the canvas finally needs a good clean then you can following following few steps that were refered to us by a reputible canvas company.
Due to the fact that most canvas is pre-treated to resist water harsh chemical cleaners and other heavy cleaning products will damage the fabric.
Recommended is a mix of mild soap woolite, sugar soap… and cold water. Just make sure there are no detergents in it. With a soft brush apply the mixture and let it soak for a while then grab your trusty hose and rince it clean.
If your looking for some stain removal instructions you can do the following: One cup of bleach, 1/4 cup of mild soap and 2 litres of water. Apply it with a soft brush, leave it for 14-18 minutes and then rince clean with a hose.
There are also some brand name cleaners you can get a the local marine store, and these will do the job just as good if not better, but the above mixtures should do the job at a fraction fo the cost.
Just make sure you air dry the canvas and never machine dry it as it will shrink.