None of these products are marketed as color preserver, but anything that seals the thread so epoxy can't penetrate should work to do the job. How well they hold up under different circumstances remains to be seen. What this testing was meant to show is how effective the 4 different products are. I wanted to give them very little chance of doing the job as a color preserver just to see how effective they were in a worst case scenario. One product looks almost foolproof if you actually did proper wraps (packing/burnishing) and 2 coats even if it is cut 1:1 with water to thin it.
UV testing would need to be done on some of these but I'm not at that stage in the process yet.
I was also looking at how well original color was maintained and there was a clear winner there too.
I thought some of y'all might be interested, so I thought I'd share it here.
I'm not making any sort of recommendation on anything, just showing some testing/results:
https://youtu.be/H1jubPw4jLM