It's important to note that yellowing that results from oxidation is entirely different than the yellowing caused by UV exposure. Oxidation is caused by oxygen exposure and causes the hardener to discolor. Once ArtResin cures, it becomes inert and the hardener will no longer react with oxygen or yellow further. UV light damage causes yellowing in cured epoxy resin. ArtResin is chemically engineered with two different types of UV inhibitors to offer the best yellowing protection on the market.