2.0lbf EPS blank sealing

So this is my first board done in EPS, now that im done shaping im about to glass, ive looked around swaylocks for a few days and people seem to either say glass without sealing or seal first using micro balloons or spackle. Im thinking about spackling the deck, but leaving the bottom bare. . My thinking is that it will help prevent delam but keep the deck nice and white with no holes ( im keeping the deck white, doing a blue swirl on the bottom) also, ive read that keeping the foam bare allows for resin to seep into the pores and makes for a stronger board. So im kinda thinking im just going to spackle the deck. Im also going to run a vent on the leashplug, so i think it should be alright in the sun with delam. What do you guys think?



Here's what I know.  Spackling is fine for a surfboard. I have never had one delam. Leaving eps 2lb open pored will make a heavy surfboard. if you want that then don't spackle.


Spackling makes the board cosmetically better. it preps the surface for paint or whatever.


Spackle keeps the epoxy from soaking too far into the blank. But spackle doesn't keep epoxy from soaking in. Spackling is perfect for eps and making a board light.


Not all 2lb is equal. There are many different kinds of EPS, ie.,different fusing, bead size etc.   So with that said, I spackle all my eps blanks. 

 I spackle with DAP Fast n Final.  Use this product.  Anyrhing else will give you grief.  using other products might be the source of this "EPS Delam Mumbo Jumbo"


Mix it down with distilled water, Why Distilled warer.....we do this so it doesn't turn brown and make the pretty white spackle do wierd shit.  Mix it to the consistency of peanut butter.

Spread it on with a bondo spreader.

Put it on very thin over the entire board, don't build it up. all you are doing if filling up the voids between the beads.  Let dry.

Now sand the board with 220 grit so just the top of the beads are showing, but the spackle is in between the beads and filling the voids.

There you have it, you can do a swirl, or a paint job, or just leave it white. all is good.


No need for a vent plug, thats just silly

My little bit to add (or at least, confirm the above): Pay attention to that “distilled water” recommendation, because I shrugged it off the first time I spackled and just used tap water, and I got some a beautiful yellow-brown resin swirl on the board that I wasn’t planning on. Distilled water is important.


Everything Resinhead said is what I do… with the exception that I thin it down further than peanutbutter. I thin it to the point where it just runs, and it’s not like putty. If a huge piece tears out, and I’m filling in a big gouge, I’ll use it straight out of the tub for a first coat, then skim it with a thinned coat a second time.

But as lemat said in another thread, if you want the ultimate seal coat with the added benefit of buckle resistance, use a resin/glass microsphere slurry. It seems to create a resin “gradient” into the foam that actually adds strength.

i did one without sealing thinking it would have the best bond but maybe making it a bit heavier. well it did not come out any heavier but i did have issues with pinholes and had to do an extra fill coat to properly seal it up. have not had any bonding issues with spackle but have seen it on others boards with heavy spackle and paint.....

tried one with epoxy/microballons and was not a big fan. messy and hard to get a good even coat. i havent had any issues with spackle bonding so i dont know if this made the bond any better? although some claim it makes huge difference. seems like it should be a good way to do it which is why i tried but my skills/processes were lacking....

I don’t have problem with light spackle too. I care to spread it thin and sand it to foam. But as i say in the other post, my test show me that it’s not a bond difference but more a stiffness/buckling difference. In test sample made with still fluid epoxy/micro were stiffer and need more force (8% more) to break than spackled one. I noticed that both sample break for same displacement, that explain why stiffer one nedd more force. In fact both sample break because compress side buckle when foam separate. Separation appear deeper in microepoxy sample than in spackled one. In fact i just put in evidence something Greg Loeher says for long time…

For me spackling is a really efficient methode, fast easy and clean, micro epoxy seems better for stringerless boards.

Sorry for my frenglish


Indeed. The real value of a stringer is adding buckling resistance. So the difference of using micro epoxy will be bigger on stringerless boards.

Also on very thin boards we’ll go without sealing, glass the board very dry, and then when the resin thickens we’ll do a cheater and fill in the weave.  This gives a very good bond, better buckle resistance and the resin doesn’t soak into the blank too bad.  It doesn’t make the most cosmetic board going, we only have done this on team boards. But it does work for boards that are very thin and are going to be ridden hard.

No sealing,  lots of bubbles in the lam.   All you need is to fill the spaces between the beads, so it’s an extremely thin coat and you need to get a feel for the correct consistency whether a slurry or spackle.

nj_surfer says…

So I’ve had issues with spackle then attempting to do a resin tint; the tinted resin seems to ‘find’ the spackle and make those spots darker. So I want to do another resin tint this spring but was thinking about doing the whole spackle seal and then doing an epoxy slurry on top well after the spackle dries and is fully sanded. What could go wrong?

I’ve found that spackle gets mushy if there’s a ding.

I’ve been using straight primer paint to seal the blank so that the vaccuum suckers can hold the blank down on the machine - still lots of pinholes but the vac holds.

I’ve primed with Zinsser white undercoat and microballoons mixed to a slurry. The finish is nice and sandable. The epoxy seems to stick fine on the boards. I’ve snapped two stringerless with 2X4ox top and bottom done this way so have not tested the adhesion for more than a few months. I’m back to putting stringers in.