epoxy chemistry question

[porthos]

why do some epoxies require a 4 to 1 mix (resin/hardner) such as brownells acraglas. brownells acragel is a 50/50 mix. i have two different system 3 epoxies. one is 50/50 the other is 2 to 1 mix. inquireing minds want to know??

[HWooldridge]

In general, fast hardening epoxies tend to shrink more - slower reaction glues shrink less - but in the end, the final chemistry is whatever the manufacturer wants to use in the recipe.

[bangerjim]

Yes.........just follow the printed directions from the maker printed on the package.

And buy the SAME brand/type of epoxy in the future and not several brands/types. Makes life much simpler.


banger

[Kosh75287]

And unless you're pretty well versed in organic chemistry, the more you learn, the less you'll know.

[gwpercle]

J-B Weld Epoxy ... the original Cold Weld , slow curing kind , twin tube 50-50 , that is gray in color is best and has the strongest bond .

The fast drying stuff has less strength .
Gary

[Battis]

I've been using West Systems epoxy for many years - boat repairs, house repairs, etc. They have a slow and a fast hardener (3-1 mix). I use the fast hardener when mixing small amounts, slow hardener for bigger jobs.
They have a knowledgeable and helpful tech department.