The first step is to mix up a batch of two-part epoxy resin. This is used to seal the open foam core of the board. You can use whatever resin system you like - just mix the resin according to the directions on the bottle and make sure you measure carefully. We happen to be using West System 105 epoxy resin.
Some things to think about when mixing resin for the first time are:
- How much resin will I be using for this step? Small batches are better then big batches since the pot life of most resins will be between 15 and 30 minutes once they are mixed.
- Are all my project pieces in place?
- Does this resin need to be thickened for this application? If you are going to be applying the resin on a vertical surface, or are wanting the resin to act more like a filler (like bondo) then you'll probably want to add a thickener agent, like carbosil, or fairing filler as I will refer to it in the next step.
Once things were prepped, we mixed our epoxy resin system according to the directions and applied a liberal amount of the resin with a brush onto the entire area where the inner core foam was exposed and then allowed it to dry.
It's best to lay down this primer coat of resin that will penetrate the project surface before adding in any of the thicker resins that contain fillers so that they'll have something to grab on to.