Plumber Putty - not for plastic?
 

I am converting an Eheim compact 600 to be inline and was planning on using plumber putty to seal the seam on the barb that I am putting in. The label on the plumber putty says not to use it on plastic (the pump housing is plastic).

What should I use instead?

I would think JB Weld would be good. It takes a day to dry but is very tough.

Seal the seam? You mean the protrusion on the barb, from manufacturing? I usually trim that off with a sharp knife.

Otherwise a silicone adhesive (like GOOP) ought to do. Plumber's putty would be a bad choice.

Plumber's putty (AKA stainless putty) stays soft and is only good for light duties like drains and sink flanges where disassembly is expected. It's Plasticine.

It seals well against plastic, even glass.

Do you mean kneadable 2-part plumber's epoxy (widely: epoxy putty)?

This cures brittle and sticks well to nothing but itself and your fingerprints. I don't even trust it to rough iron drain systems without a primer coat of regular (syrupy) 2-part epoxy.

If you want a permanent bond, regular 2-part epoxy will do it. Even the 5-minute epoxies are very tough and stick to anything dry.

JB Weld is a solvent-based 1-part glue that would work too.

Based on your advice it seems like I will be using JB Weld.

Thanks

JB Weld is a 2-part epoxy resin adhesive...

indeed, he still can't get things right it seems

I wouldn't use JB Weld in an application like this. It gets brittle and when you move your system's tubes around I am afraid you'll get a pinhole leak. JB Weld works pretty well for patching up cracked impeller housings and the like though. For what you're proposing I suspect that silicone adhesive (aka Plumber's Goop) is probably the way to go.

agree with plumbers goop; its good for everything. an alternative is to get a $2 tube of water pump RTV silicone from your local auto-parts store.

the "Goop" that I know of is solvent cement, not silicone RTV (sealant)
for strength I prefer Goop

So JB Weld is to epoxy what Xerox is to photocopy? Just curious as I've never used it, and trust your experience more than what's touted on the package.

***

BillA. Several times you've said Kobuchi belongs on your ignore list. Well?

Don't use JB weld on plastic for a sealant.
http://www.jbweld.co.uk/
http://www.jbweld.co.uk/files/prodb.html

Should I pick up generic plumber goop at home depot or is there a brand name I should look for?