Problem with Triple Thick yellowing over time?

[PinkRockSugar]

So, I've used TT to seal my pony's eyes since I started doing customs. And I just noticed lately that almost every pony I've used it on that I still have, the TT has yellowed, badly. Like there are one or two that it didn't happen with, but the rest, I had to very delicately peel and pick the TT off. It didn't always come off easily, and now I have quite a few ponies who need their eyes retouched or repainted completely.

Has anyone else ever had an issue with yellowing Triple Thick? Is it an issue of time? Exposure to sunlight? The kind of paint I use (water-based acrylics)? Could a bottle of TT go bad? The bottle I'm using is a few years old, I guess. Should I bother trying a new bottle, or is this just a characteristic of the product?

[Nemesis]

I'm not familiar with Triple Thick, but I do know that many (if not all) sealants carry the risk of yellowing. It can be a result of environmental factors such as temperature or humidity, but I don't think anyone knows for sure what other issues (such as UV exposure) may cause it. Try to apply/dry the sealant in a controlled setting if possible, as the root of the problem sometimes starts when a doll/pony is sealed in less-than-ideal conditions.

Hopefully someone more knowledgable about TT can offer you more specific advice... Sealants are such a pain.

[Uninu]

I had one gloss that yellowed over time, too. It wasn't TT though.

The one I use at the moment is from Vallejo and I haven't noticed it yellowing. I have some doll heads that have had Vallejo gloss on them for years and there is no change in them.

[pyrodarknessanny]

Of they are full body repaints.
Did you seel the base paint before up applied the whites for the eyes?
 

[PinkRockSugar]

Yeah, I seal the bodies with Dullcote when the painting is finished, then I do the hairing, and the TT was the very last step. Do you think it's a reaction to the Dullcote?

[pyrodarknessanny]

Is TT UV stabilized? 

[PinkRockSugar]

I'm not sure! I'll have to do some research. If not, maybe there is an additive I could use.