How to Make a Permanent Patch on a Broken Tent
Dry and cozy in your sleeping bag, you hear the first drops of rain hitting the rainfly. You go back to sleep. You wake up when the wind picks up and the sides of your tent begin to shake like a flag waving in the breeze. That’s when you notice the wet floor. You feel the windward side of the tent wall and discover a small tear. Through the tear, a constant stream of water flows down the inner wall and pools on the floor. Unless the rain lets up soon, you know you’re in for a night of mopping and wringing. When your tent dries out, you know you’ll need to make a repair.
To repair or not to repair
Our discussion here is limited to repairing a tent, rather than repairing seams, grommets, or frames. Any discussion of how to mend fabric should begin with a discussion of the fabric itself because not all fabric is worth repairing. Whether it’s nylon, canvas, or vinyl, tent fabric is susceptible to a number of diseases that weaken the fabric to the point that it can’t be repaired. When you repair an area with a patch, the stress that caused the original tear is simply transferred to the fabric surrounding the patch. If the surrounding fabric tears, you’ve wasted your time repairing. Before attempting to mend a tent, pull on the fabric surrounding the tear to make sure it doesn’t rip either.
Preparing the surface
If you determine that your tent fabric is in good condition to hold a patch, the next step is to prepare the area for patching. Both nylon and canvas are woven, and sometimes vinyl is fiber-reinforced; tears often leave ragged, frayed edges. Use scissors to cut out the frayed area; if necessary, cut through the intact fabric until all frayed edges are gone. You are going to stick the patch on, so clean around the damaged area with denatured alcohol to remove any fabric treatment and dirt. Clean both sides of the fabric. If the tent is vinyl, lightly roughen the surface around the tear with fine sandpaper to increase the adhesion of the glue.
make the patch
The best fabric for a patch is the fabric that matches your tent: use a canvas patch for canvas, a nylon patch for nylon, and a vinyl patch for vinyl. Cut the patch twice as long as the tear and at least several inches wide on each side of the tear. Cut the patch into an oval shape, because the square corners will tend to peel off when the tent is flexed. It is important that the patch is large enough. Patches that fail do so along the edge of the patch, because the fabric flexes more at a point where a larger thickness (the patch) meets a smaller thickness (the fabric). To avoid failures there, make sure the edge of the patch is far enough away from the damage that the charge is reduced enough.
paste the patch
Glue is the best way to apply a patch, because when you use glue, the fabric doesn’t fray and the repair doesn’t leak. The best patching glue is one that reliably adheres to fabric under all conditions (heat, cold, humidity, packaging, etc.). Latex cement is often touted for repairing tents, but avoid it; does not adhere very well in extreme conditions. Contact cement works well, but can be a bit stiff. The glue recommended by tent rental companies is called Barge Rubber Cement, made by the Quabaug Corporation. It can be purchased at Ace Hardware and most hardware stores. Barge Rubber Cement stays flexible in almost any condition it can find and for long periods of time.
Paint the glue on the back of the patch and on the area surrounding the damage. Give the solvents in the glue a few seconds to dry, and then press the patch onto the fabric. Make sure the edges of the patch are well glued. To make sure the patch is well attached, support the fabric from below and hammer the patch with a rubber mallet or roll it over firmly with a roller or veneer roller. For best results, patch the damage on both sides of the fabric.
Allow the glue to dry before packing the tent for storage. While you’re doing the repair, put some of your repair supplies in a plastic bag and pack them with your tent; You never know how far from home you’ll be the next time you need to mend a tear.