Video
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This video shows a creator setting the finboxes and coating the bottom of a surfboard with fiberglass and epoxy. He does not chat during the video, but the video offers a detailed view of the process.
The fin boxes are set in epoxy and that region has two layers of fiberglass to give it extra strength.
The creator does a really nice job of wetting the fiberglass hanging over the side of the board. Its worth noting that he gets the fiberglass fully wetted on one side by pouring and scraping the epoxy over the edge. Before wrapping that side, he proceeds to wet the lap on the other side. Getting that fiberglass fully wet is so important for a clean lap. Dry spots are very hard to wet out once you've pressed the fiberglass up against the bottom side.
Another thing to note here is that to make it easier to complete pressing the lap, he lifts the board (on one end) so that its easier to see and squeegee the epoxy.
The creator has not taped the bottom of the board and its surprising how clean his edge is on the underside of the board. If you ever work with fibreglass and warp it under the as he is doing on this surfboard, its challenging to do such a clean job. You are likely to pull strands of fiberglass from the edge and these strands will tangle at the edge or collect on your squeegee making it difficult to keep a clean edge.
Since the creator is wearing a gas mask, it may be that this is not epoxy, but instead a polyester resin. I didn't see that explicitly noted in the video. Polyester is easy to work with, but it outgasses toxic vapors, so you really need to be careful with it. This is not as common with epoxies, but can be depending on the specific epoxy. Polyester is really only water resistant, epoxy will be stronger when cured and provide much better water resistance. Also, you need to be careful not to mix your resins. Epoxy will not bond as well to a polyester surface. If the bottom coat is polyester, the top coat and repairs should use it as well.
You don't see the creator when they are sanding the tip, tail and the edge of the lap. Fiberglass a mask should be worn. Its easy to forget this, especially if you just think, I'm only sanding a small bit.
When coating the top surface with fiberglass, the creator rubs a few sections with his fingers. I would presume he is doing this to make sure the fiberglass and underlying surface is fully wetted. Once the fiberglass is wetted, any air pockets underneath are only going to get cleared if you squeeze them out. A squeegee will often not fully exhaust a smaller air bubble.