Builders' Forum Archives
Re: Epoxy safety
Posted by Laszlo on Jan 29, 2008
I'm not a chemist, so someone who is may be jumping in to correct me, but my understanding is as follows:
The carboxyl group on the end of the acetic acid reacts with the amines in the hardener to form amides and ammonium carboxylate salts. The remaining gummy mess is a mix of unreacted vinegar, epoxy and hardener, as well as the incompletely cured epoxy.
Vinegar residue will definitely weaken the next batch by starving the epoxy of hardener. It may even completely prevent it from curing. Scrupulous cleanliness is always necessary for best results.
In theory, any organic acid with a carboxyl group should have this same effect, but vinegar is probably the best choice because it's cheap, easily available and non-toxic.
Finally, vinegar only works when there are unreacted amines present. Properly mixed and fully-cured epoxy is impervious to vinegar.
Hope I haven't stretched the truth too far,
In Response to: Re: Epoxy safety by Ian Colledge on Jan 29, 2008
- Re: Epoxy safety by Ian Colledge on Jan 30, 2008