Epoxy is easy to use, but it's not goofproof.
If you think you did everything right, but you still ended up with a soft, sticky mess instead of a solid surface, one or more of the following things might be the cause.
- Inaccurate measuring
Precise measuring of the epoxy resin and hardener components is essential for a proper cure. Epoxy can be measured by weight, by volume, or by using the set of metered resin and hardener pumps available with many epoxy systems. The easy-to-use pumps are calibrated to measure the exact amount of resin and hardener, so you don't have to guess, and you get a reliable cure every time. - Added more hardener than indicated
Epoxy cures properly only if you measure and use the exact amounts of resin and hardener specified by the manufacturer. A common mistake is thinking that the resin will cure faster if you add more hardener. Adding more hardener will give you an uncured mess. If you want your epoxy to cure faster, use a hardener with a fast curing speed, or make the temperature of your work area warmer. - Components weren't mixed thoroughly
In addition to measuring the resin and hardener components precisely, you have to mix them thoroughly or you'll either get a soft cure, or no cure at all. Dispense both parts into a clean container and mix thoroughly for approximately three minutes. Scrape the bottom and sides of the container to ensure that the resin and hardener are combined properly. If using fillers, stir the resin and hardener thoroughly before adding. - Contamination
Water in the resin mix can cause an improper cure. For example, condensation can form in containers stored in a cold environment and warmed quickly. Other contamination sources include dirt, dust, and accidental cross contamination of resin and hardener components. - Combined incompatible products
Unless specified by the epoxy manufacturer, do not mix components from different manufacturers and expect the mix to cure properly.