Chapter 60: How to Seam Seal a Tent and Other Outdoor Gear
Seam sealing your tent will make it more waterproof and help it last longer.
To seam seal your tent, set it up outside on a sunny day. Some people tell you to apply seam sealer on the outside of the tent and some say inside. Most tent makers and seam sealing instructions tell you to seal seams on the urethane-coated side of the fabric, which would be on the inside. That way, you’re forming a completed seal of the coated side of the fabric.
You should apply it where you can best get at the stitching. That would mean sealing butted seams on the outside and lap felled seams on the inside. The needle holes are the area where there is potential for leaking. If in doubt, seal both sides. It never hurts to add strength to the inside and outside of your seams.
Use a proven seam sealer like McNett Seam Sealer and Outdoor Repair, or Kenyon Seam Sealer 3, or Aquaseal Seam Seal. McNett is the most widely used. These products are to be used on nylon tents that are polyurethane-coated.
For tents that use silicone-coated nylon, use McNett Sil Net or make your own sealant with GE Silicone II Clear Tub and Sink Caulk. The GE Silicone II should be mixed in a one-to-one ratio with mineral spirits, preferably the odorless kind. It can take quite a while to get this mixed to a smooth consistency. You may want to use a paint stirrer in an electric drill.
Most silicone-coated tents like Six Moon Designs and Tarptents should be sealed from the outside.
Prepare the seams by cleaning them with isopropyl (rubbing) alcohol.
Apply with a small brush or syringe. Many people like the extra control they get with a syringe. You can purchase a syringe at a pharmacy or art supply store.
If you are using McNett Seam Grip on a urethane-coated tent, you can mix the sealer with Cotol-240 an accelerator that gives you a 2-hour cure time. This makes it easier to finish and fold the tent without folding sticky seams back onto the tent.
Seal all places where attachments are sewn to the fly including webbing, Velcro, snaps, guy-outs, and zipper tracks. The sealer will make these points not only more weatherproof, but stronger, too. Your tent should be sealed all around the inside perimeter of your tent floor.
In time, seam tape can peel and fail. It can be reapplied with Seam Grip. If the tape is failing everywhere, remove it, clean with rubbing alcohol, and seam seal normally.
Sleeping bags have a tendency to slide on a silicone-coated nylon tent floor. So, if you are sealing a silicone-coated tent, it’s a good time to add some strips or dots of sealer to the tent floor to reduce sleeping bag movement.
Allow your tent to dry thoroughly before folding and storing. If the seams seem tacky, you can add a little unscented talcum powder.
Seam sealing your tent is quick and easy, and it will add to the life of your tent.