Seam Grip vs Seam Grip + FC: Which Sealant?
By Six Moon Designs | Published: 2026-10-17
Category: Comparisons
Compare Seam Grip and Seam Grip + FC for tent seam sealing. Learn which fast-cure sealant works on polyurethane-coated shelters and why silicone-coated tarps need a different product.
Quick answer
Use Seam Grip + FC (Fast Cure) only on polyurethane-coated tents and tarps, such as the Skyscape Scout or Lunar Duo Outfitter. Do not use it on silicone nylon or silicone polyester shelters. For silicone-coated tarps like the Deschutes, you need a silicone-compatible sealant such as Seam Grip + Sil (SilNet).
What is Seam Grip + FC?
Seam Grip + FC (Fast Cure) is a sealant specially designed for polyurethane-coated tents and tarps. It cures faster than standard Seam Grip, which means you can seal your seams and get back on the trail sooner. Six Moon Designs recommends it specifically for their Skyscape Scout and Lunar Duo Outfitter shelters.
Why compatibility matters
Not all seam sealants work on every fabric coating. Seam Grip + FC bonds well with polyurethane (PU) coatings but will not adhere properly to silicone nylon or silicone polyester. If you apply it to a silicone-coated tarp, the sealant may peel off or fail to create a waterproof barrier. Always check your shelter's coating before choosing a sealant.
Tradeoffs at a glance
- Seam Grip + FC: Fast-cure formula designed for PU-coated shelters. Cures quickly, saving time on the trail. Best for PU-coated tents like the Skyscape Scout and Lunar Duo Outfitter.
- Standard Seam Grip: General-purpose sealant that works on many materials but cures slower. Not ideal for silicone coatings either. Consider only if you have a mix of PU gear and need a single tube, but check compatibility first.
- Silicone-compatible sealant (e.g., Seam Grip + Sil): Specifically formulated to bond with silicone-coated fabrics. Required for tarps like the Deschutes. Essential for silicone nylon or silicone polyester shelters.
Product facts
- Seam Grip + FC (Fast Cure): Seam Grip + FC Sealer is specially designed for polyurethane coated tents and tarps. It works great with our Skyscape - Scout or Lunar Duo - Outfitter tents. Warning: This product should not be used on Silicone Nylon or Silicone Polyester tarps and shelters. If you own a PU-coated shelter, this is the correct fast-cure sealant. Using it on a silicone-coated tarp will not create a durable seal.
- Deschutes Ultralight Backpacking Tarp: The Deschutes is a no-frills tarp shelter, everything you need and nothing you don't, providing the ultimate freedom. At a mere 13 ounces, this pyramid-style design is incredibly stable providing 360° protection in some of the most extreme conditions. The Deschutes is a silicone-coated tarp. Do not use Seam Grip + FC on it. Instead, choose a silicone-compatible sealant to maintain its waterproof performance.
Which sealant fits your shelter?
Best for
- PU-coated tents and tarps that need a fast-cure sealant
- Six Moon Designs Skyscape Scout and Lunar Duo Outfitter owners
Not for
- Silicone nylon or silicone polyester tarps and shelters
- The Deschutes Ultralight Backpacking Tarp or similar silicone-coated gear
