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FABRIC DAMAGE 5 - Repairing holes in canvas pack fabric.

To disassemble and then neatly repair any pack or bag by stitching a patch over the damage is very time consuming, often doesn't look great when it has been done (unless whole panels are replaced) and can be very expensive if done by a commercial repair service. For complicated or extensive repair work the cost could be as much as half or more of the new replacement cost of the item. For all but structural damage repairs modern adhesive-sealants provide a simple, convenient DIY solution.

This page relates to canvas repair but is almost identical to the one for the common heavier-weight nylon fabrics like bulked-filament Kodra and Cordura, and multi-filament, nylon oxford. The difference is that canvas has no PU coated side. See the separate DIY page related to these fabrics.

A liquid PU adhesive-sealant is an indispensable part of any outdoor repair kit and SeamGrip® is the go-to product in this category, although it is possible to find cheaper alternatives. Available at nearly all outdoor retailers we carry SeamGrip on longer trips and keep a tube at home in the fridge. It adheres to just about any textile or coating other than the 'rubbers'. These exceptions include silicone elastomer coated fabrics (see the separate page on repairing them), Hypalon® and latex.

You can apply the PU adhesive-sealant to either side of canvas but, for the sake of appearance try to work on the inside of the pack or bag. Make sure the area is clean and free from dust. Next, tape over the hole or tear on the opposite side to the one you will apply the sealant to. Masking tape works well for this, readily obtainable from the paint department in your local hardware store. Use it to hold the torn edges in alignment. Rub it down firmly to achieve a good grip. In some cases it may be easier to place a piece of a plastic under the repair area, like polyethylene ice cream container which the PU sealant will not really stick to. Note that a PU like SeamGrip will span a small hole quite well (see illustration). In this case you should try to build up some thickness in the adhesive by several applications.

SeamGrip can be applied over the tear directly from the tube. For long thin applications it is much easier and neater to apply the liquid with a 10mm syringe. Squeeze the amount needed into the back end, fit the plunger, invert and expel the air. Because SeamGrip flows under its own weight the repair area must be flat and perfectly horizontal. Place weights, clamps or tape out the repair area on the flat, level surface.

Badly abraded canvas, perhaps involving multiple layers of worn through fabric and maybe part of a seam can simply be filled or 'glued up' with the PU compound. Again, several applications may be needed and, in this case, it may be easiest to work on the outside of the bag. The illustration at bottom right is Kodra nylon and we have placed a block of wood inside the pack bag so the thin nails can be used to stretch out the repair area which here is on a bulky seam.

You can also glue a canvas patch in place with SeamGrip although the added fabric layer and thickness of the adhesive makes the patched area very stiff. Nevertheless it is easier than stitching (which, for canvas, should always be done with the correct thread and as small a needle size as possible).

The PU adhesive-sealant cures by absorbing moisture from the air. It usually needs to be left overnight. Smoothing the sealant with a wet finger will speed up the curing time. You can also place a piece of cling-wrap, PE or PP plastic sheet OVER the sealant (and weight it down) to produce a nice flat finish on an outside repair. In this case it is a very good idea to wet the sealant first but still allow longer for the adhesive to cure.

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