Posted by KBS Coatings on 7/22/2025 to
News and Updates
How To Seal a Plastic or Polyethylene Gas Tank
Rigid plastic and polyethylene fuel tanks can develop fuel weeping or leaking over time as the material degrades. KBS Gold Standard Tank Sealer, used with KBS Klean and Fusion SEP, seals the inside of the tank with a tough, fuel-impervious liner that stops leaks and protects against future fuel seepage.
Here is the modified Tank Sealer process for Rigid Plastic Tanks:
- Clean the inside of the rigid plastic tank well with KBS Klean. Rinse. Let Dry. Bone Dry.
- Pour an amount of Fusion SEP into the dry tank. Slowly rotate and roll the tank until all interior sides are evenly coated. Patiently work with Fusion SEP for up to 10 minutes, then drain out all excess. Fusion SEP is designed to promote adhesion and goes on in a very thin film.
- Follow Step #3 from the KBS Tank Sealer Application Directions. Be very careful to avoid letting the Tank Sealer puddle.
Plastic Tank Size: Up to 5 Gallons
- 8 oz of KBS Klean
- Pint of Fusion SEP
- 8 oz of Tank Sealer
Plastic Tank Size: 6–12 Gallons
- Quart of KBS Klean
- Pint of Fusion SEP
- Pint of Tank Sealer
Plastic Tank Size: 13–25 Gallons
- Quart of KBS Klean
- Quart of Fusion SEP
- Quart of Tank Sealer
For complete step-by-step instructions, visit the KBS Tank Sealer Application Directions page, or learn more about the full KBS 3 Step Tank Sealing System.
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Questions?
If you have questions about sealing your plastic fuel tank, contact KBS Coatings — we're happy to help.

