There are two common reasons why the epoxy didn't cure: incorrect measuring and incomplete mixing. Measuring and mixing is really easy with most System Three® epoxy systems because they mix at a 2:1 or 1:1 volume ratio, but this doesn’t mean you don’t have to pay attention to what you’re doing. First , read the label or Technical Data Sheet to see what the correct ratio is for the product you are using. Customers will call our Technical Support line suggesting that something is wrong with the epoxy because it didn’t cure properly. We know of no situation where properly-mixed resin/hardener has gone bad or has been contaminated and wouldn’t cure. In the majority of cases, it turns out that the batch was either incorrectly measured or insufficiently mixed. Epoxy chemistry just will not allow it to work any other way.
If you’re working on a project that requires you mix many small resin batches, develop a measuring technique that is sufficiently accurate and stay with it. Doing it the same way each time will minimize the chance for error.