It is possible to polish epoxy. It just isn’t as ‘hard’ as other materials, so you have to be more patient. I used the same grit progression you did, but on the first few grits, to get an idea of how long you have to spend on each, use a magic marker/sharpie. Mark the entire board, everywhere. It is hella fun for the kids, and they can say they helped. Just doodle all over the place. Definitely for before 320 and before 400. when you have taken off all of the sharpie marks, you know you have have gone far enough on that grit. I used to do the same thing when I made optics for a telescope, so you know when to switch grits, as all work done while making optical surfaces is done wet.
After the sanding, I used 3M super duty rubbing compound, with a $30 sander/polisher from harbor freight. I used a wool pad, looks like carpet. Then with Fiberglass supply’s surfboard polish #2. Use a different wool pad for the polish. Came out like so: (if I uploaded the pics right).
I cannot stress enough that you have to wash the board between every grit/compound so that remains of rougher grits don’t keep scratching your surface. May seem like overkill, but it worked for me. Again, stuff I learned making optics.
Your other deal, if it was possible to lay on a coat that just sets glossy; it is possible, just requires the right environment. Any dust shows up as the ‘zits’ you see on the coat. Unless you are in a filtered room wearing a lint free jumpsuit and hairnet, hard to do. So, we wetsand out the defects and polish. But, if you have a decently clean room, and an incredibly clean board, here’s what I do (soulstice helped me a bunch with this):
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Measure out your epoxy resin (I now use a scale, hard to find good accurate cups)
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Measure 1cc AddF per ounce of resin (same as 2cc per ounce of hardener)
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Measure 1cc denatured alcohol per ounce of resin
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Measure 1cc X-55 accelerator per ounce of resin
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Warm the resin, around 2 seconds in the microwae per ounce of resin
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Put your hardener in the container, measuring it on the scale as you go, if you are off a gram or two, no problem, but try to be accurate. It’s not difficult.
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Stir for around 30-50 sec, slowly enough that you do not whip bubbles in the mix.
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As you keep stirring, add the AddF, DNA, and X-55, I do it one at a time.
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Stir for another 30-50 sec, and filter the mix, this is very important. I use the paper paint strainers you can get anywhere. You will be amazed at the amount of junk left in the strainer.
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Use a clean brush, wet the brush with the strained epoxy before you start, and get it all on there, 2 sets of cross-strokes & final walkout (per roger brucker), watch out for bristles in the coat. Brush slowly enough not to leave a ton of bubbles behind the brushstrokes.
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If you see any bubbles, you can get them with a heat gun, like the black and decker paint stripping gun. PRACTICE with the thing on something that is not important, as you will see that if you leave it on a spot too long, it will crater the coat’s surface, but just enough, and you will see bubbles you didn’t even know were there pop. You will need light at the right angle to see this. Only do this if the coat is still ‘runny’ enough, before it ‘gels’.
It helps to have a warm surface to coat on, really helps everything flow. A hotbox or just leaving the board out in the sun for a little while helps (benny1’s idea). Make sure whatever you use to warm the board doesn’t get dust on it, or zits wil appear. If you have a warm surface, you can skip the DNA in the mixture. I use it because I often coat without a warm surface, to get the mix a little thinner, and I could never get the board warm without getting it dusty.
Hope this helps. I have come close to getting ‘perfect’ coats, but always have some zits and a bristle, eyelash, bug, etc in there.
I always enjoy looking up at the night sky when I get a chance, haven’tr been able to afford a decent scope yet and as for making my own… well… maybe that is a project I will take up one day. I’m sure like surfing your own board, seeing one of the planets or a nebula through your own handcrafted scope must be quite a feeling.
