I bought mine at Ace Hardware. Ace is the place! ha. Well anyways, I found two different kinds. One is polyurethane based and the other is water based. The helpful person at Ace told me that you can't use polyurethan on plastic. So, since I have plastic PEX pipes I opted for the water based product that does the same thing. Not sure if this is the correct answer, but it is something to look into...
Tim Marshall
2004 3670RL Montana
2002 F-350 powerstroke diesel
