Builders' Forum Archives
Re: really old epoxy
Posted by Mark Camp on Oct 11, 2004
And finally, we stitch and glue types NEVER call epoxy hardener "catalyst" :-) That's for that nasty, weak, waterlogged polyester stuff that Dad accidentally stuck himself to the dinghy with in the 60's.
Serially though, there is an occasional misconception that epoxy hardener acts like the catalyst in the polyester system. If it did, then that batch of MAS goo that we mixed 2 to 1 instead of 1 to 2 would cure really fast, instead of (sob) never.
Polyester resin is like a room full of giant lego blocks, and the catalyst is like a bunch of kids that run in and build a wall out of them, then leave. More kids, the wall gets built faster, but the wall is made of lego blocks, not kids. Carter? Are you in there, Carter? OK, made mostly of lego blocks, plus little Carter.
Epoxy resin is more like a pile of those plastic I-beams in a Conexx set. Hardener is like the little plastic cubes that hold exactly x number of beams together. If you have too many cubes (four pumps of CLC hardener instead of one), they have nothing to connect, and they are stuck in the middle of the structure messing it up. Too few connectors, then many of the I-beams (resin molecules) have nothing to connect them together, and again they hang around in the middle of the structure making it a mess.
In Response to: Re: really old epoxy by Howard on Oct 10, 2004