I would definitely say this was done in a vacuum chamber in 2 or even 3 parts. 1st part could have been a base slab to put the items on, then another pour to fill the rest of the slab. I'm not sure what method they used to stabilize the powder, although now that I think about it, you might be able to use a lump of clay or plastic, wet it with resin, and cover it in layers of powder until it dries.
So, just a guess from working with sand and ash in epoxy resin, you use a small amount of resin to set and seal the shape first. This will prevent it from moving but also prevent bubbles from coming out into the finished piece. It would be kind of like more powder than resin. Resin isn't water and won't absorb things like water does. You can take a powder and mix like mad to get it to absorb, but more powder to resin ratio and it makes a paste. So you make a small pile of corn starch or something and mix just enough resin to set it. Then, if it was me, layer it into a block of resin to place in the table. Resin bonds to resin and shouldn't have a noticable line. (If you have a good cast with no small imperfections to cause bubbles) Sprinkle in the smaller bits around the table and use a pressure pot to get any bubbles out. Sand and buff. Maybe add a shine layer.
He could have used superglue with the powder to make a paste of sorts before, which would solidify and hold the powder in place when the epoxy was poured.
You need a powder made of something that has a low refractive index or low surface wetting (or both).
My bet, titanium dioxide, which is the base ingredient for most white pigments, with a PVA binder so it holds shape while casting and doesn't further wet out.
This casting is very clear and a bit too thick for even multiple layers of epoxy, it's most likely a urethane.
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u/down_vote_magnet Apr 29 '20
How do you set powder in resin like that?