Board is weak. Epoxy glosscoat?

My first longboard with Resin Research epoxy came out great. In the second (2 lb. EPS, 2 x 6 oz. top, 1 x 6 oz. bottom), I ended up sanding into the weave over large portions of the bottom and rails. The lam and hotcoat turned out poorly, which meant I had to sand heavily to get things flat and smooth. As a result, the board feels “soft” in certain areas, especially the bottom, to the point where pushing hard with your thumb can leave a permanent dimple or pressure ding.

The board (it’s the blue one below, the other one is the one that turned out well) has been waxed and ridden several times. Because of its weakness, it now has many small, shallow dings on the bottom from handling and being bumped. I’m also concerned that water might soak in over time in the areas where there is exposed weave.

As a minimum, I was thinking I should remove the wax and do an epoxy gloss coat over the whole board. The board has a polished finish, so I will need to sand it to prepare a surface for the gloss coat to bond to.

My main question is: what grit should I sand the board with? Obviously a heavy grit will compromise the fiberglass even more. But how fine a grit is too fine for bonding of epoxy on hardened epoxy?

Also, I’m going to do everything possible to get the wax off before sanding and gloss coating, but what is some wax has gotten into the exposed weave? Am I at huge risk of the epoxy not bonding to those areas…?

Any advice appreciated!

By the way, I learned an important lesson - rushing to make the delivery deadline is not worth it if it means compromising the board in any way!! Should have done the gloss coat while the board was new and unwaxed!

adding resin wont make the board stronger

you really need to put on more cloth

Completely agree with Silly. Extra epoxy resin will be flexible & mushy, like doing a bad job of ratios on your lam. You need to sand off as much of the hotcoat as you can and lam on one more layer of glass, nice & dry, and then give it a fill coat within about 4 to 6 hours after it starts to harden… You should sand your board with the goal being smooth surfaces & clean curves, without concern for the weave, and then your additional lam & hotcoat will be smooth enough to need very little sanding.

The good news is, you’re extremely unlikely to get some of the ‘typical’ epoxy issues like pinholes, air bubbles, foam soaking, etc…

Thanks for the input. I will do as recommended and add a layer of glass for strength.

Question about the 4-5 hour fill coat: What is the procedure?

  1. lam bottom

  2. while epoxy is still soft, fill coat bottom

  3. flip board and lam top

  4. while epoxy is still soft, fill coat top

OR:

  1. lam bottom

  2. when bottom is hard, flip board and lam top

  3. fill coat top while epoxy is still soft

  4. when top is hard, flip board

  5. rough up top with sandpaper and do fill coat on top.

Or something else (Is it possible to lam both sides first and still have time to do the fill coats before it’s hardened fully?)

The first option seems the most straightforward but I was wondering if it would be problematic to such a “built up” lap (from the lam + fill coat) when going to start the lamination on the other side of the board… am I making sense? I’ve read in other posts about the benefit of doing the “quick fill coat” but the order of steps was not specified.

I’ve done both ways, but generally opt for #1, though a lot of it depends on my garage temperature.

If its really warm (like 75*F +) and will stay that way, I’ll do option 2 (although thinking that in step 5 of choice 2, you meant “bottom” not “top”), knowing that everything will be done within 24 hours & benefit from some chemical bonding (crosslinking?).

But more typically for my part of the world (Northern California) overnight temps are around 55 (11 months of the year or so) so it’ll be a 2-day project. In that case, I lam the bottom & fill it & then wait. Next day, flip it, scuff off the laps & tape line with a surform (far less dust than by sanding), scuff the fill coat an inch or so past the tape line, clean it all up with a dry, non-linty cloth, and lam & then fill the deck. My laps up from the bottom come around the rail farther than the ones down from the deck. All I’m really shooting for here, is getting the deck lam down on the bottom’s fill coat within 24 hours, which is usually doable. Like day 1: lam at 6 pm, fill at 10 pm; day 2: flip & prep at 5 pm, lam at 6 pm, fill at 10pm. All the fill coats get the benefit of heated resin, so they flow out thinner & smoorther but then also grab into the lam stickier (true, it seems) and set up quicker once they start to harden.

Thanks so much for explaining your procedure. Yes, in step 5 I meant “bottom” instead of “top”, sorry…

Here in Florida temps are usually warm enough that I should be able to do option 1 most of the time.

I’ve never laminated over a finished board before so this will be interesting. I guess I will use less epoxy as it won’t be soaking into foam. Other than that I assume it will be more or less the same as laminating on foam.