If you have a tent, tarp or pack made from silicone-coated fabric or “silnylon” material (fabric that has been infused with silicone) the only thing that will bond to it is silicone. When repairing this type of gear you will need a specialized adhesive, like Sil Net.
Sil Net is a silicone-based seam sealer for use on silicone-coated and silnylon fabrics. Sil Net permanently seals seams on silicone treated products. Sil Net will flow into seams and “self-level” providing a good looking seam seal.
Seam Grip is a waterproof seam sealer that is permanent and cures in 8-10 hours. It is ideal for use on natural fabrics, leather, vinyl, waterproof laminates, PVC and synthetic fabrics including polyurethane, nylon, neoprene and rubber. Seam Grip is unaffected by heat or solvents and will typically outlast the fabric it is applied to.
Seam Sure is a water-based seam sealer that cures in 4-6 hours. Seam Sure is specifically formulated to seal seams on larger family-sized tents and easily glides over big areas of material with its unique applicator brush. Seam Sure does not have the permanency that Seam Grip has and can be broken down by solvents if necessary.
IMPORTANT NOTE: Many manufacturers will offer "silicone-treated" fabrics to keep clothing and gear lightweight and waterproof. However, unlike true silnylon fabrics that have silicone infused into the fabric, these silicone-treated fabrics typically have a silicone coating on only one side (outside) and a polyurethane coating on the other (inside). If you are unsure which side of your gear has been coated with silicone, contact the manufacturer. Once you know which side is which, you can treat accordingly.
Seam Sealing Tips
We recommend making repairs or seam sealing from the inside mainly for aesthetic reasons. If the polyurethane coating is on the inside, use Seam Grip seam sealer. You do not need to seam seal both sides, so applying Seam Grip to the interior of your silicone-treated fabric will suffice.
A standard 1 oz. tube of Seam Grip will treat approximately 144 linear inches when using a quarter-inch bead. Use Seam Grip for smaller 1-3 person tents (i.e., backpacking tents) and Seam Sure for large family tents or tents that are used less frequently. Seam Sure’s water-based formula allows for easier application and a standard 2 oz. bottle will typically treat 280 linear inches of fabric using a half-inch bead.