If you're going to try making your own backpack or tent at home, you're eventually going to have to seal the seams! You can buy expensive seam sealer, or, you can make your own. I prefer the latter option. It's also great to use when you make any repairs to your tent, as you'll want to seal those, too. Here's what to buy: - a tube of 100% silicone clear sealer - mineral spirits And that's it! Then: 1. Mix a 50/50 mixture of spirits to silicon in a glass jar or bowl. Stir with a stick or other wooden tool to mix. You may need to add more sealer or thinner to get a consistency that's kind of like thick paint. 2. Don't mix more than half a cup--it goes a long way. 3. In a well ventilated area, spread the item out and coat both sides of the seam with a foam brush. If you can only do one side at a time, let the first side dry for a few hours, then flip it and do the other side. 4. After a few hours of drying, you'll have a waterproof item! Tips: - Pitch your tent or tarp a bit tighter than usual and let them dry standing. - You'll get it on more than the threads of the seams, so try to do about 1/4" on each side of the seam for the best sealing. - Get rid of extra sealer. The mixture doesn't hold up well; you'll just have to remix next time. - Store the materials in the house somewhere it doesn't get too hot or too cold, or the chemicals in the ingredients will be ruined. Good luck!