Flexseal Tube Sealant

Flexseal is a two-part urethane-based sealant designed to help eliminate porosity and wicking problems in inflatables made of materials such as Pennel Orca®, Hypalon®, neoprene, EPDM, PVC, and urethane. Flexseal will not harden or crack, is not affected by freezing, and remains flexible to -40°F.

Note: Flexseal will not cure large punctures or seam leaks.


  • Raft Sealant Kit

Recommended Safety Precautions

  • Work in a well ventilated area (garage or shady area works well)
  • Use a respirator and chemical-resistant gloves, preferably Nitrile, or heavier rubber gloves.

Boat Preparation

  • Work area should be at least 60°F
  • Inflate boat very firmly to check for leaks. Use soap/water solution to check for pinholes. A glycerin/water solution will find the smallest pinholes. Large, high volume leaks will need to be repaired before using Flexseal.
  • Very Important: The inside of the tubes must be dry before pouring in the Flexseal. Water will ruin uncured Flexseal. .


  1. Measure equal volumes of Part A and B and pour into a container. Mix thoroughly.
  2. Flexseal is usually added to the tube through the fill valve. Remove the fill valve and pour the desired amount of Flexseal into the tube. Try to avoid getting Flexseal on the inner valve piece (if you do, it should peel off after it cures). You can use a funnel to pour the mixture in.
  3. Reinstall the valve and inflate the tube.
    CAUTION: Exercise care when adding Flexseal through a PVC valve (mouth valve). Flexseal will bond to PVC and any excess sealant could ruin the valve.
  4. Distribute sealant along the area of the tube you want to seal by rocking and rotating the tube. Deflate tube and knead the area to evenly distribute the Flexseal. You will feel the fabric sliding on the sealant. It is best to take a methodical approach in kneading to assure uniform coverage. Work problem spots a little longer.
  5. Inflate tube to ½ inflation and let set 24 hours at 60°F. Warmer temperatures will decrease cure time. It is important to exchange the air in the tubes several times during this period to release solvents. Do not allow the tubes to collapse and touch while Flexseal is curing.
  6. If porosity is still a problem after 24 hours, a second application will usually remedy the leak.

Note: If sealant has dried on valve parts and is creating a problem, the sealant usually can be peeled from the valve.


  • Store unmixed kit in a cool dry location. If Flexseal freezes, warm to room temperature and mix thoroughly. Shelf life is two years.