I am working on my first epoxy inlay and have encountered an issue. I both overfilled and underfilled portions of the inlay cavity. In the underfilled regions (non sanded), the finish is glossy and the sparkle from the mica powder is visible (green arrow in attached image). The overfilled regions were surfaced with the CNC router then sanded with 220 grit sandpaper. These regions have a cloudy/dull finish (red arrow in attached image). How do I completely fill the inlay cavity and get the mica powder sparkle? Do I need to use higher grit sandpaper? Polish it?
Higher grit sandpaper is the answer, and to start low and work your way up through the grits. 220 is usually fine enough for wood but it’s not once you start working with plastics.
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NewsVan is correct. You can use a Micro-Mesh set and go all the way to 2000 and you will have a glass like finish.
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Thanks for the feedback! I will give it a try.
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Or go even higher 
Brass splines in my walnut drawers I went all the way up to 12K. I’m not saying to go that high, but to first thousands maybe…
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FWIW, when I polish the finish on one of my guitars, I sand through 6000 and then polish/buff with fine and ultra fine polishing compound. Number one rule is do not skip any grits and make sure to sand thoroughly with each grit to remove the scratches left by each grit. You can move up more or less by approx 1/2 the value of the grit you just used, so for example 220 > 360 > 400 > 600 > 1000 > 1500 > 2200 > 3000 > 4000 > 6000 etc. would be about right. Takes a while, but it’s the only way.
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Thanks for the suggestions.
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After a lot of research, experimentation, and spending of time and money, I finally found the perfect way to achieve that glossy epoxy finish—just like it looks right after being freshly poured—even after having to sand or surface it down when pouring into wood.
I watched Blacktail Studio’s videos on polishing river tables to perfection, and tried everything from sanding up to 8000 grit to using products like Brasso and Mother’s car polish. But despite all that, I still couldn’t get consistently great results.
Then, a friend who restores classic cars shared a game-changing tip with me: automotive clear coat, specifically the “2K” version, which is a two-part system with a base and hardener.
This stuff is incredible, and I apply it using a regular airbrush. Think about it—the colored paint applied to cars at the factory is actually dull and rough. It’s only after they hit it with a couple of layers of clear coat that it comes to life.
I visited a local wholesale automotive paint supplier that sells retail over the counter, explained what I needed, and they recommended the brand and model of clear coat in the photo below. It’s a 4:1 mix (or 1:4 depending on how you see it), and once it cures, it’s rock-solid. Clear coats on cars are designed to withstand physical impacts, so this stuff is just as durable, if not more so, than the epoxy itself.
And the shine? Wow! This clear coat is just as glossy—if not glossier—than freshly poured epoxy. It fills in all the small scratches and pits and reflects light like you wouldn’t believe.
But here’s the best part: I only need to sand up to 800 grit, maybe 1000 at most. As long as the surface is smooth and has a frosted look, the clear coat does the rest.
Bonus tip: This clear coat is also perfect for restoring plastic car headlights. Just wet sand up to 1000 grit, mask off the headlights, and spray on the clear coat. It’s UV resistant (lasting for years) and extremely durable, just as I mentioned earlier.
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Thanks for the clear coat tip.
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I found this interesting video that shows the sanding progression.
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Yep! That’s the way. You could easily go past 2500 also because as you get higher and higher, the work becomes easier. Applying the compounds (or something similar) with a powered buffer/polisher will yield better results too.
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