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Step 13: Hotcoating the Deck and Bottom

The hotcoat is a layer of epoxy that will be apply over the fiberglass lamination, it fills up the visible weave of the fiberglass and seals up the surfboard. To get a good hot-coat it is important to apply the epoxy at at least 15C and ideally at room temperature. Do it in an area with no drafts and ideally a dust free area if possible. Vacuum up as much as dust as possible if you are hotcoating in the same area as you sand, including the surfboard.

Start by wiping down the sanded areas of the surfboard with denatured alcohol and acetone. Then apply a piece of masking tape at the mid point of the rail, this allow for a nice clean hotcoat line, reduces drips and saves effort when sanding. At the tail of the board, leave the hard edge un-taped.

Get a chip brush ready by smashing the bristles into a piece of masking tape to pull out any loose bristles.

Mix up some epoxy same as the glassing step but reduce the amount by 1/3 as a rough guideline. Also I added some additive F to the epoxy, this is an agent that helps reduce fish eyes and makes the hot coat better, trust me this stuff works.

Pour out the epoxy onto the surfboard and using the chip brush plow the epoxy around on the board, making sure to cover all areas of the board evenly including the rails. Then using long even passes go up and down the surfboard, then using cross strokes go across the board working your way down from the nose to the tail. Then wipe around the rails with the brush and fill in any missed areas. Look the board over to see if any spots were missed it should be nice and even. The whole process should only take a few minutes, once done, leave it alone, sometimes the more you mess with it the more you can screw up the hotcoat.

After a few hours come back and check the board, when the epoxy is tack free, the masking tape was pulled. Let the surfboard sit and harden.

Once the deck hotcoat is hardened, flip the surfboard and then apply a layer of masking tape just below where the previous tape line was, maybe 1 mm below the other line, so a bit of epoxy is showing. At the tail of the board create a tape dam so some epoxy can collect at the edge of the tail, this will be used later for sanding a nice sharp edge.

For the bottom hotcoat, mix and apply epoxy just like the deck hotcoat. Pull the tape once the epoxy has become tack free. Let harden.