Cleaning ‘Extreme’ Mould Off Canvas (Tents, Campers etc)

MOULD…… the campers worst enemy!

If you have a canvas tent, camper trailer or have canvas sections on your wind-up, pop-top or expander caravan then you may have experienced the dreaded curse of mould!

It’s not nice to look at, spoils the appearance of your canvas, devalues your investment and worst of all its dangerous to your health. It CAN make you quite sick. Asthma, respiratory problems and allergies.


What causes mould? Mould is caused by moisture that saturates or is left to sit on surfaces or remains as wetness / dampness in fabrics. Warm air, dust, dirt and moisture causes mould to develop. Mould spores then spread in the air and can travel to other areas.

If mould is left untreated it can eat away the water proofing properties, cause unpleasant stains of your canvas and eventually rot your canvas.

Obviously prevention is better than cure, but sometimes its impossible to catch mould in time before it becomes a significant problem. Manufacturers will always recommend you never pack up a wet canvas product or at least ensure it is set up again when you get home to clean and let dry completely before putting it back into storage.

It only takes a small damp patch for mould to start taking hold and once it does – you need to act fast.

If you trawl the internet you will find hundreds of home remedies and suggestions of how to kill mould on canvas.

Ideas to try are:

  • 1/4 teaspoon of oil of cloves per litre of water in a spray bottle for cleaning mould from hard surfaces. Lightly mist on, leave overnight and wipe off.
  • For soft items mix one kilogram of uniodised salt in a nine-litre bucket of water. Paint over the item, leave until a salt crust forms then wipe off with a soft brush.
  • For cleaning mould from canvas, try tablespoons each of bi-carb soda, white vinegar and methylated spirits, and two teaspoons each of eucalyptus and glycerine.

It is important to kill the mould and the spores to stop mould growing, but it does stain the canvas if left to get too severe. I would always recommend trying to kill the mould before attempting the technique that I will outline below.

We travel in our Jayco Eagle Outback full time, it gets exposed to harsh weather of all kinds, and after spending time in FNQ with hot, humid days and nights of heavy rain our canvas copped a hiding. Mould started to appear, particularly at the bed ends when things like pillows and doonas may rest against the canvas. When this happens the pillow or doona etc acts like a ‘wick’ and helps draw the moisture in through the canvas fibres. Nights with a heavy dew is major cause of mould for many campers too.


Although a good quality canvas is waterproofed at the factory which is deeply impregnated into the fibres, waterproofing can wear our. Heat, sun, rain, humidity all has an adverse effect on the waterproofing and the constant folding of the canvas during pack ups and set up can speed up the deterioration process. No one expects the waterproofing to last forever, so keep in mind it may need to form part of a maintenance item on your canvas.

One thing you will read about when looking at ideas to clean the mould on canvas is advice about not using harsh chemicals. They DO strip the waterproofing from canvas, but that’s not the end of the world. You CAN re-waterproof your canvas simply and without too much fuss and like I mentioned above- its a maintenance thing!

Bleaching alone is not recommended as it does not kill the mould, it only bleaches the colour so it can’t be seen- not ideal!

If mould has taken hold on your canvas and you have tried the myriad of Googled suggestions without luck or perhaps they did work but you are left with a nasty stain, then you may like to try the next step. The following process DOES include using chemicals, it DOES strip your waterproofing, it DOES have bleaching properties, It DOES need to be done with extreme care and is done at YOUR OWN RISK! But it works!!!

You may want to try a test section of your canvas before committing to cleaning the whole lot and I repeat, you do this at your own risk.

This process is a 2-3 day process and requires sunny, dry weather. It’s best to do this in a well ventilated area, use plenty of old sheets etc to cover any furnishings and protective equipment should be used such as gloves, eye wear and perhaps breathing masks if you are sensitive to chemicals.

Step 1.

Prepare canvas areas by removing as much fabric furnishings away from the area as possible. Curtains, lounge cushions, bedding etc and cover non, canvas areas with old sheets, towels etc to protect them. The chemical has bleaching properties so be warned!

Using warm, soapy water and a sponge, scrub the canvas area to get it as clean as possible. Do BOTH sides (in and out) and allow to dry completely.

Step 2.

mould offUse gloves, eye wear and face mask, apply ’30 Seconds Mould Off’ (available from Bunnings) to the canvas. Using a scrubbing brush, work it into the affected areas and allow to sit for 5 mins before wiping off with a wet cloth. Do both sides of the canvas. Using a soapy, wet sponge clean the surface well – use a hose with moderate spray pressure to clean the outside of the canvas. It is important that the cleaning chemical be removed entirely and rinsed well. Allow to dry.

Step 3. Once canvas has dried you should see the mould and stains have disappeared. If there are still mould stains visible then you can repeat step 2. Again, ensuring the area is thoroughly cleaned and rinsed and allowed to completely dry before starting step 4.

Step 4.

aquaproofApply COI AquaProof (available at BCF) to the canvas surface as per the directions on the bottle. Using a wide brush allows a quicker application. The waterproofing solution goes on as a white paste but dries clear. Similar to wood glue!

Ensure you get a nice even coat of waterproofing and you apply it the entire area including the sides, seams and the stitching.

We apply to both sides of the canvas and the stitching around the zippers etc. We allow to dry and apply a second coat to both sides the following day.

It’s important that the canvas is kept dry whilst the waterproofing is allowed to set/dry.


Step 5.

After a few days, use a hose to test the canvas area. You should notice water beading and running straight off. Try to soak the canvas- check for any water that may be soaking into and through the canvas and around the seams, zippers or stitching. Take note of these areas and re-apply the waterproofing as needed once the canvas has dried.


This method should be considered a last resort but may be necessary for some extreme situations. The main reason this is a last resort is because using harsh chemicals is in no way fun and repeated use on canvas may start to have a detrimental affect after heavy, repetitive use.

MOULDKeeping a coat of waterproofing solution applied (apply it regularly- once a year is a good idea) is a great way of minimising mould. Of course, making sure the canvas is dry before packing up helps too. Keeping the canvas clean will help minimise mould growth.

walk awayAs a secondary prevention measure you could also apply ’30 Seconds One Step Spray & Walk Away’ to all outside canvas sections. This can also be applied to your vinyl awnings, camp chairs, fibreglass panels and the roof/sides of your van. It’s safe for canvas and helps stop mould, moss, lichen and algae from growing on your camper, tent or caravan.

This product is similar to those used on garden paths, driveways, steps and pool furniture- but it is safe to use on canvas too. Simply spray, leave and forget!


Feel free to share this article with your fellow camping mates!



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