Note: This is the original article on which the chapter on tent repairs in The Pavilion Book was based. The book has additional information on tent repairs, but we're keeping this article on the web site because many people wanted it there.
Don't be afraid to try to extend the rip a little. If it's very easy to do, you can be sure that the cloth is not long for this world, and that any repair is not likely to hold up for long. You'll have to consider the age of the tent, the conditions it has faced (and is likely to face in the future) and how much future unreliability you are willing to put up with. Sometimes it's better to replace, not repair.
But some repairs do make sense. In fact, they almost always make sense if the defect is due to anything but cloth failure. Cloth will get punctured from a high point-load, improperly seated grommets may fail, and occasionally the tent is subjected to freak forces which it was never designed for in the first place, and which it it will likely never encounter again. A good repair here should greatly extend the life of the tent and, if properly done, will be as strong as it was before.
A rip caused by point-loading (like when an errant tent pole poked through it) is best fixed by sewing a little patch of the same material onto it. Fold over each side of the patch to keep it from fraying, and sew it to the outside surface of the damaged area. If you want to keep the damaged area itself from fraying, make the patch large enough that you can cut away the damaged area and leave enough of the tent fabric to be folded under and then sewn to the patch. (See figure 1.)
|From the outside|
|1. Cut a patch with tabs to fold over ...||2. Fold the tabs over and apply to hole ...||3. Sew the patch down.|
|4. Cut out defect, slit corners||5. Fold tabs under||6. Sew the tabs shut.|
The only trouble with this sort of patch is that you usually have to seal the upper seam of the patch to avoid leakage. This can be done with a product designed for this very purpose and available at Kmarts and sporting good stores, or with any cement which dries hard and flexible. You could also treat it with a moisture-repellent spray like Scotch-Guard or Camp-Dry, but this may require periodic re-treatment.
Another good way to patch a tear is by gluing on a patch. When you use glue, the fabric won't fray and the repair won't leak. But you must use a glue which adheres to the tent reliably under all the conditions (heat, cold, moisture, flexion, etc.) that the tent is likely to endure.
The best glue I've found is Barge's Cement, made by the Quabaug Corporation of North Brookfield, Masssachusetts. Many hardware stores carry it, and it's worth taking the trouble to find it. (No, I don't own stock in the corporation; I just like the product. We always have it in our tool box, right next to the duct tape.) It works like most contact cements, where you apply a film of it to each surface to be joined, let the film dry, and bring the surfaces together. Barge's Cement outshines the other contact cements in its ability to stay flexible after it has cured in just about any conceivable conditions you tent is likely to encounter, and over long periods of time. I've found that the strength of the joint can be greatly increased if, after you've joined the surfaces together, you beat on the joint with a hammer to fuse the films together. (Be sure to have a solid backing on the other side of the cloth, of course.) Before applying the cement to the fabric, it helps to clean the spot and the patch with denatured alcohol to remove any previous fabric treatment and the accumulated grunge of the outdoors.
If the failure is along a seam line, the best repair is to overlay a wide piece of fabric or ribbon over the rip, and sew it onto the fabric alongside the failed seam rather than onto the seam itself. This spreads the strain away from the seam, reducing the chance of the seam failing again at that point. Again, you must ask yourself whether the seam failed do to an unusual load or whether the cloth itself is giving up the ghost. I'm reiterating this because I've found that seam failures are far more often due to the latter cause than the former, and you may have to consider retiring the tent rather than repairing it.
When a grommet (sometimes also called an eyelet) fails, but the fabric it was mounted in remains intact, the repair usually consists of simply installing another grommet. If a grommet repeatedly fails at that location, you should replace it with a larger grommet, since the larger ones can better spread the load. If the grommet serves the purpose of restraining a knot in a rope that goes through the grommet, you may need to install a washer on the rope to keep the knot from passing through the new, larger grommet hole. If the grommet is a plain grommet, consider having a sailmaker or awning maker replace it with a "spur" grommet, which is designed for more rugged duty and resists separating.
When a grommet fails and takes the fabric with it, simply replacing the grommet won't do. You'll have to repair the fabric as well. I like to do this by reinforcing the area with two-inch-wide seat belt webbing and then installing a new grommet into the webbing. This webbing is thin, but amazingly strong, and is readily available (maybe even free from your local junkyard). You could also stitch in more canvas, in multiple layers. It is always better to make the patches bigger than you think they should be, since more patches fail because they are too small than because they are too big (a maxim that also works well in other areas of life, as witnessed by the miliary axiom: "A lot is good, more is better, and too much is just enough.") If the grommet is located near a hem or another cloth edge, it should be set away from the edge at a distance of at least its own inside diameter, and preferably twice that (See the axiom above.)
A patch is likeliest to fail either at its edge (if the patch is located along the edge of the fabric) or at the point where it is sewn onto the fabric. In the latter case, it's the fabric, not the patch, that actually fails. This is because the cloth flexes more at the point where a great thickness (the patch) meets less thickness (the fabric), and this flexion weakens the fibers of the cloth. To prevent failure there, make sure that the edge of the patch is far enough from the grommet (or tie, or whatever dictated the patch in the first place) that the load is sufficiently reduced. When sailmakers reinforce a high-stress area, they often use multiple patches, gradually increasing the thicknesss and layers to avoid going directly from a single layer of fabric to a heavy patch. That's also how we reinforce the peaks of our canopies -- from a single layer of reinforcement, to two layers, and then to two layers plus a thick 3" Nylon webbing.
I don't recommend leather as a reinforcement unless the use of period materials is really important to you. This is because leather, even more than canvas, is susceptible to rot and mildew. And when dry, it tends to stiffen and crack. If you must use leather, make sure it is well tanned and treated with finishers to keep it supple and resistent to decay. I've found that pigskin tends to weather a bit better than cowhide, but tears a little easier. I haven't used leather from deer, moose, or elk, but imagine that it would work well due to its toughness and flexibility.
I suppose I should cover rust and mildew stains, although I haven't had much luck with them myself. Of course, it's easy to apply full-strength chlorine and other heavy-duty chemical weapons, but here you risk damaging the cloth or the various treatments (fire retardence, water repellance, artwork, and so on) it has been given. A weak chlorine solution, followed by lots of washing, rinsing, and drying in the sun, goes a long way in killing mildew and preventing its return. But you may have to live with the stain. You could add even more artwork and, if people point out the stain to you, you say, "That's not a mildew stain. That's smoke coming from the castle at the Siege of Heidelberg, which I've depicted here in the style of Albrecht Durer." Then you pause a beat, and add, "It does look a little like a mildew stain, now that you mention it."
Rust stains sometimes respond to a solution of oxalic acid (available in some hardware and drug stores), followed by the aforesaid washing, rinsing, and drying. Remember to rinse the fabric well, followed by more rinsing and even more rinsing. Any trace of soap remaining in the fabric will combine with UV radiation and moisture in the air to greatly weaken the cloth. This is particularly true of synthetic cloths, but applies to natural fabrics as well.
A bent pole should be replaced. If it's more than two diameters out of column, it's no no longer strong enough to be in your tent, because much of its strength in compression is gone. Sometimes you can strip the finish off the pole (if indeed it had any in the first place), wet the pole, and hold it in a straightening jig until it's dry. If you do this, re-finish the straightened pole immediately to keep the pole from absorbing moisture.
A broken pole can be sleeved. A good rule of thumb is to make sure the sleeve is six times longer than the diameter of the pole it repairs (that is, a pole two inch thick needs a sleeve twelve inches long, with six inches above the break and six inches below it).
If the metal extension (the part that goes into the grommet) is falling out of the top of the pole, you can glue it back in with epoxy. Or you can use a polyurethane glue like Titebond II. These new glues expand within the space between the metal and the wood and provide an extremely durable bond. I like to clean out the hole a bit with a round wood rasp or file to remove any weak wood in the hole, figuring that the glue joint is only going to be as strong as the wood that it joins. (That's the old "A chain is as strong ..." principle at work.) Again, make sure the top of the pole is well varnished to stabilize the wood and eliminate the shrinkage or swelling that caused the metal pin to come loose in the first place.
Parts made of rope or PVC pipe are usually not worth fixing. Just replace them. I know that PVC is wonderfully easy to repair using PVC glue and various fittings. But since the break was usually caused by the pipe getting old and weak, you again run into the problem of fastening a sound repair to a weak structure. If you enjoy repairing rather than replacing, feel free to do so; you can look forward to many hours of enjoyment because that pipe is going to keep breaking over and over again until you replace it. The problem with PVC (or EMT thinwall conduit, for that matter) is was that it was never really designed to be a structural member. It was designed to be easily bent and to hold stuff inside it, not to take any great loads.
The easiest repair to make is the one you don't have to make in the first place. If you carefully follow the set-up and care instructions that came with your tent, it's quite likely that you'll never have to repair it at all. This is very easy to say, of course, and very hard to accomplish. If this were a perfect world, bad things would never happen to good people (and tents), but that's not the world we were issued, is it?
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