I use 5 minute epoxy mixed with fine sanding dust to glue in my inlays. I just did a huge gothic L inlay in an ebony fretboard for a bass I'm building. After all that work, I'm always so worried that the epoxy will stay soft and sticky. After 5 minutes it sets up, but it usually takes a few days for it to get hard enough to sand down. Is this normal? I'm using equal quantities of resin and hardener. Is it possible that adding the ebony dust is affecting the curing time?