All corners were sealed with silicone. I used some clear silicone that I had it on hand. I see a lot of recommendations for using a color so it is easier to see. One thing I discovered in this first pour, when they say it needs to be water tight, they mean it needs to be water tight. If you can not fill it with water and put some gold fish in it, you’re going to have epoxy everywhere!!
Be careful not to leave globs of silicone. They will show as hollows in the epoxy edge.
I wanted to fill some cracks with black epoxy first, so I made a dam out of silicone so I could get the level slightly above to ensure the void was completely full and could be sanded even.
The wood will float in the epoxy so it needs to be clamped or weighted down. One mistake I made was not covering the blocks holding down the walnut. I wound up epoxying them together. I had to cut and plane them off. Any pieces like this should be covered in tuck tape(Tyvek tape).
Then I did not get enough downward pressure to keep the blue epoxy from going under the walnut. This is what the underside looked like. Almost a 1/4″ of blue epoxy.
I have since made a bunch of tuck tape covered wooden blocks.
Since the rocks were just above the blue in a clear pour, when I planed the blue off to get back to walnut I ruined a set of planer blades. Luckily they were due to be changed anyhow so no real harm, but a good lesson learned. I should have gone with a simpler design for the first board.
I had a matched piece of walnut that I glued to the back to make it thicker again. I then repoured the blue in the new bottom.