Dry and comfortable in your sleeping bag, you hear the first drops of rain hitting the rain fly. You go back to sleep. He wakes up when the wind picks up and the sides of his tent begin to shake like a flag fluttering in the breeze. That’s when you notice wet soil. You feel the windward side of the store wall and discover a small tear. Through the tear, a constant stream of water flows down the interior wall and collects on the floor. Unless the rain stops raining soon, you know a night of scrubbing and wringing awaits you. When your tent dries up, you know you will need to do a repair.
To repair or not to repair
Our discussion here is limited to mending a tent, rather than repairing seams, grommets, or frames. Any discussion of patching the fabric should start with a discussion of the fabric itself, because not all fabrics are worth repairing. Tent fabric, whether it’s nylon, canvas, or vinyl, is susceptible to a number of maladies that weaken the fabric to the point where a repair won’t hold up. 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 rips, you’ve wasted your time making the repair. Before attempting to mend a tent, pull the fabric around the tear to ensure that it also does not rip.
Preparing the surface
If you determine that your tent fabric is in good condition to contain a patch, the next step is to prepare the area to be patched. Both nylon and canvas are woven, and vinyl is sometimes fiber-reinforced; tears often leave ragged, ragged edges. Use scissors to cut the frayed area; if necessary, cut undamaged fabric until all frayed edges are gone. It will stick the patch, so wipe around the damaged area with denatured alcohol to clean off any fabric and dirt treatment. Clean both sides of the fabric. If the tent is vinyl, lightly scrape the surface around the tear with fine sandpaper to increase the adhesion of the glue.
Making the patch
The best fabric for a patch is the one 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 length of 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 large thickness (the patch) meets less thickness (the fabric). To avoid failure there, make sure the edge of the patch is far enough away from damage so that the load is reduced enough.
Stick the patch
Glue is the best way to patch, because when you use glue, the fabric doesn’t fray and the repair doesn’t leak. The best patch glue is one that will adhere to fabric reliably in all conditions (hot, cold, wet, packing, etc.). Latex cement is often touted for tent repairs, 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 from Ace Hardware and most hardware stores. Barge Rubber Cement remains flexible in almost any condition you may encounter, and for long periods of time.
Paint the glue on the back of the patch and in the area surrounding the damage. Let the glue solvents dry for a few seconds, 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 tightly with a roller or veneer roller. For best results, patch the damage on both sides of the fabric.
Let the glue dry before packing up the tent for storage. While doing the repair, put some of the repair supplies in a plastic bag and pack them with your tent; You never know how far from home you will be the next time you need to patch a tear.