How to Waterproof Cotton Canvas Tents and Tarps

It is wise to waterproof cotton canvas tents and tarps since moisture, humidity, and high temperatures resulting in mold and mildew are all factors in the ruin of many outdoor canvases. Mildew is by far the most common threat and is virtually impossible to remove. Mildew normally occurs when fabrics are repeatedly exposed to moist conditions with poor air circulation and high humidity. Since outdoor canvases are most often stored in places with just such conditions, the best way to prevent damage to your cotton canvas tents and tarps is to treat them with a waterproofing solution prior to storing them.

First, purchase a waterproofing spray made for waterproofing cotton canvas tarps and tents such as Kiwi Camp-Dry or any other brands that are available at most camping supply stores, hardware stores, and discount retailers like Wal-mart. These sprays coat the canvas with silicone to prevent water from saturating the fabric. Depending on the size of the canvas, several cans of the spray may have to be used to treat the entire piece. Each can will treat approximately 200-250 square feet and generally costs less than $10 per can depending on the brand chosen. Be sure to check the label on the can to determine if the product you have chosen is appropriate for use on the fabric you are treating.

Next, make sure your canvas is clean, dry and free from loose dirt and debris. Most canvases can be cleaned with warm, soapy water made with a mild detergent and then air dried. Additional cleaning may be needed if the canvas has already been exposed to mold or mildew. Read the manufacturers cleaning instructions that came with your tent or tarp to prevent damage.

Then, find a smooth flat surface on which to work. A deck, driveway or lawn would be ideal. Make sure to pick a day when the wind is calm to ensure an even distribution of the waterproofing spray and when there is little chance of rain as most treatments will require at least 24 hours of drying time in order to effectively waterproof your cotton canvas tents and tarps.

Next, hold the spray can approximately 6-8 inches away from the canvas and apply in long, smooth, even strokes being careful to avoid drips and runs. Be sure to cover the entire canvas and pay close attention to the edges as well. Allow drying time according to the sprays instructions.

Lastly, after the first side has been treated and well dried, flip the canvas over and treat the underside. After allowing plenty of drying time for, re-treat both sides of the canvas again for extra protection. When canvas has been fully treated, your waterproofed cotton canvas tarps or tents are ready for outdoor use, but you might need to reapply periodically to ensure optimal protection.