The best way to clean canvas is with bleach. Bleach can be used as a cleansing agent and it is effective in removing mildew growth on canvas as well as killing the mildew spores, as long as you follow a few simple guidelines.
Proceed Safely
Read the safety directions on the bleach bottle label before commencing and follow directions carefully. Wear rubber gloves and be careful to avoid contact with skin and eyes.
As some tenting fabrics are not colorfast, you should test in an inconspicuous section of the tent with the mixture before proceeding, as some tenting fabrics are colour fast, but not all.
The treatment is best performed outdoors and the best way to clean canvas, as well as making it easier to apply the mixture, is achieved when tents, annexes, etc. are up and taut it is also best if the tent is fully erected.
If you have a Karcher or similar gadget that could be the best way to clean canvas it could make it easier and quicker.
If you are not able to erect the tent then spread the tent out on a clean surface.
Remove dust and dirt by lightly brushing. Heavy soiling should be washed off with clear warm water but do not use soap, detergents or other cleaning agents.
Application
The bleach should be diluted with water, 1 part of bleach to 3 parts of water, it should not be mixed with any other chemicals or cleaners.
Apply this bleach solution evenly to the outside at a rate that will penetrate the fabric, working it into the canvas with the Karcher similar gadget or a soft brush or broom.
Hose off thoroughly after 15 minutes, continuing to hose down after run off is clear.
Repeat If Necessary
If mildew is not completely removed, allow canvas to dry, and then repeat the application.
Do not allow the bleach solution to remain on the canvas for more than 20 minutes without thoroughly rinsing or damage may occur.
Bleach does not reproof, but acts as a pre-treatment to removing mildew and spores. Once the canvas is completely dry, the canvas is pre-treated and ready for an application of your chosen reproofing compounds
