I just laid the first coat of epoxy on size D Guidebrod champion nylon thread in a grey color. I laid on three coats of U40 CP first, and let it dry overnight about 12 hours, and after the first coat epoxy was laid on, the thread has darkened irregulary, with what can be described as “tiger striping” . Oh well, I guess I’ll learn to live with it, and call it a “special effect”

What went wrong here? And how to avoid this in the future? Thanks

Did you thin the color preserver? That's a no-no.

Are you certain the first coat was a full, wet application?

The only other thing I can think of would be failure to property stir the CP or if it had thickened in the bottle, leaving you with mostly water rather than the solids that do the work.

.............

Thanks, the CP was a little lumpy, but a new bottle. I removed the lumps with a light brush touch, dunno

The other possiblility is that the wraps were not tightly wrapped or not burnished to push them together. This sometimes looks like CP that didn't work well.

Another possibility is that the CP was very old and may have lost some of its protection. I don't know if this is a realistic possibility, but if your CP was more than a couple years old, I would be suspicious.