There are thousands of different types of plastics and polyethene's in use today and they continue to change every year. Because there are so many out there, it is impossible to test all the plastics and polyethylene for adhesion and compatibility. Therefore, we cannot completely recommend our tank sealer kits for soft or flexible plastic or polyethylene tanks.
What we have found over the years is that many soft or flexible plastic and polyethylene tank owners are so desperate that they have been willing to try it regardless of the results. The surprising thing is that most, but not all, have great results. The success is due to the fact the more porous the soft or flexible plastic or polyethylene, the more it leaks. But this also means the more porous the plastic, the better the gas tank sealer can stick because our Tank Sealer loves porous surfaces.
In conclusion, we cannot recommend our tank sealer kits for soft or flexible plastic or polyethylene fuel tanks. But, if you are desperate, you can certainly give it a shot.
You can find complete directions for the KBS 3 Step Tank Sealing System here: https://www.kbs-coatings.com/tank-sealer-directions.html