How to Re-Waterproof Your Tent
TO REMOVE WATERPROOFING
Before you can apply new waterproofing you'll need to remove the existing coating. Place your tent into a large vessel - bathtub-washtub-vat. The tent may need to soak a few hours to get the coating all off - use a detergent such as WOOLITE® although any household detergent should do the job. You can use a front loading type washing machine like you find at coin operated Laundromats; but do not use an agitator type as it can damage your tent (rip seams etc.) [Since it may take several applications to get the entire waterproofing chemical off, it probably isn't practical to use a washer at a Laundromat]. Once the old coating is off, the tent will need to be well rinsed and set up to dry.
There are a number of products on the market today that were developed specifically to recoat synthetic or man made fabrics such as nylon, dacron, & polyester. Most are water-based and easy to use. Some are brush-on or paint-on products and others are sprays. It's a good idea to read the labels on the individual products to see what they recommend. The brush-on/paint-on ones require more planning as the drying time is quite lengthy.
Brush or Paint-on
¢ Apply the new coating to the outside of the fabric (the original was on the inside) in a well-ventilated area. Your tent should not be set up when applying the coating as the substance is wet and will run - it needs to be done on a flat surface. Use a medium bristle brush or a soft roller to evenly spread the coating so there are no runs or puddles. Each area will need approximately 72 hours of drying time at 70 degrees before folding fabric.
¢ Keep the coating container tightly capped when not in use; typically these products do not degrade in the container. Keep brushes wet at all times during application, then clean them promptly in tap water.
¢ Remove existing waterproofing as above but make sure to read the manufacturers instructions. The most common problem with sprays is holding the can too close & causing runs that may go undetected until they dry. These runs will cause problems, as they'll never dry completely. When folding a tent that has little globs of undried coating those spots will stick together and will be hard to pull apart - eventually the fabric will rip.
¢ Drying time is not as long with sprays, but it is still critical to be completely dry before folding the tent.
After applying any waterproofing it is a good idea to apply talcum powder or cornstarch very lightly before folding the tent the first time. If there is any tackiness this will help to alleviate it and prevent sticking.