The sticky spots are areas that did not cure properly. The four main reasons epoxy doesn't cure the way it's supposed to are:
- Incorrect mix ratio - TotalBoat TableTop Epoxy has a mix ratio of 1 part resin (A) to 1 part hardener (B), by volume (or 100A:83B, by weight). If this mix ratio is altered in any way, the resin will remain sticky.
- Improper mixing - Epoxy resin and hardener components must be mixed thoroughly. If not, you may have resin-rich or hardener-rich areas that will remain sticky and not cure properly. To help ensure complete mixing, stir for at least three minutes in one clean mixing cup (it's important to scrape the sides and bottom while mixing), then transfer to a second clean mixing cup and stir thoroughly for another three minutes. This 2-cup mixing method ensures that both components are mixed thoroughly.
- Improper temperature - Mixed epoxy requires specific temperature conditions for curing. Epoxy takes longer to cure in colder conditions, or may not cure at all.
- Surface contaminants - Any surface contaminants can cause an improper cure. Chemicals or substances that may seem harmless can alter the epoxy's reaction, and in some cases, prevent the epoxy from curing.
If the spots are fairly small, remove them by using a small paint scraper to carefully scrape away the sticky epoxy. Wipe the surface with a clean, lint-free rag wetted with denatured alcohol or acetone, and allow to dry. Mix a small batch of epoxy (using the 2-cup method), and pour a thin coat over the affected areas. You may need to repeat this process in about four hours to ensure the new coat(s) are level with the existing epoxy.