As soon as coating or casting epoxy resins are exposed to UV light, whether we talk about direct or indirect exposure, the resin you use might be at risk of discoloring, some products more quickly than other higher-quality epoxy’s.
Fortunately, the epoxy industry has evolved a lot, and there has been a significant advancement in using the right combination of UV absorption with HLAS.
This perfect combination of components is quite effective in slowing down the yellowing effect of UV simply by absorbing the light.
Tip: Adding a touch of a blue tint to any clear casting or coating epoxy. This will help to avoid the nuisance of a yellowish tinge.
If you are using the resin in an outdoor setting well, a UV stabilizer is necessary. Nevertheless, these additives will strengthen color stability but exposure to the sun’s UV rays, even filtered, or florescent lighting will affect the color in the end.
Anyway, epoxy with additives for UV protection does most definitely protect against yellowing. It’s hard to be sure about how long these UV stabilizers last. It can be a few months, even years, but never a permanent thing.