I'm working on a desk for my wife that uses a big live edge walnut slab for the top. There's a big honking knothole that needs to be filled. No big deal. I've done epoxy fills before. It's always worked well, until now.

I'm using Alumilite Clear Cast (link) with a drop of black dye. I've used it in the past with good success.

The first try I mixed it up and added a couple drops of india ink. I poured, popped any air bubbles, and looked forward to picking the project up when it hardened in a day or two. Two weeks later it was still soft, about the same durometer as the rubber on a tire. I chalked it up to the solvent in the ink.

I dug it all out and mixed another batch. Ratio was watched very carefully and I mixed thoroughly. I added a drop of Transtint Black, as the Alumilite instructions indicated compatibility with alcohol based inks and dyes. A week later it's very soft and sticky like tar.

My shop is in the basement, and temperature is in the mid to high 60's. I warmed the fill up with a hair dryer as Alumilite suggests cooler temps will retard the hardening process. We'll see what it looks like tomorrow.

I've had the epoxy material for at least a couple years. Could I be bumping up against a shelf life issue? Any other words of wisdom from those that do this regularly?