spackeling EPS technique...

ok, so let e first by saying that i have shaped less than a dozen boards completely on my own. hooweer on thins ive always had a problem with is ge-gassing then spackling my eps blanks. the ulra-light weight epoxy has been just a pain in the ass to work with.

so i decided to mix a good deal of water in a quart mixing jug with some spackle and stir the hell out of it until it was the same consistency. i then poured it over the board and basically squeeged it off just like it were a hot coat. with two down in this fashion, i must say that it seems to be working great, i have little or no de gassing, and the board is as light as ever. no to mention saving my boat loads of time.

just wanted to share and get some advice/feednack.


In the words of the great gymnastics sports announcer, “You nailed it”

Most folks try to put it on too thick and strugle. Mayonase consistency, and put it on like a lam job with a squeegee. Some hits the floor. But you can move it and smooth it easily. Little to no de-gass.

Anyone tried using the grouting sponges sold at home centers for smoothing up your spackle job before letting it dry? Just dampen it and use it to smooth out any ridges, lumps etc. Helps blend it in and makes sanding easier after it is dry. I have also been adding Gesso when thinning the spackle with good results. This tip was from Atomized and is discussed I believe in another thread.


Dave D

gesso? chile con gesso?

What is gesso and where do I get some? Good call on the sponge thing. I’ll try it.


Gesso is white paint with calcium carbonate added to it as a filler. It’s used by artists to coat canvas before painting on it. You can thin it and paint with it as well. You can find it at almost any art store.

Dave D

great, thx.

You like it better than water to thin with?


I still use a little demineralized water along with the Gesso. Its similar to adding some white airbrush paint to the spackle but I believe the Gesso has more calcium carbonate in it. The cal/carb is what makes for a flatter (less glossy) finish. A good quality Exterior flat latex will work as well. The binder in the paint/Gesso is similar but better than whats in the Spackle. Search for posts by Drewtang and Atomized on the use of spackle.

Dave D

very good. I thought I knew it all. I’m usually not right when that thought pops into my head.

You can use the same method with resin and filler. Too thick and it becomes hard to work with. Too loose and it soaks into the foam. Somewhere in the middle and it goes on just as easy as diluted spackle.

When I do use spackle, I use the lightweight stuff that’s like Fluff… you know, the stuff you put on sandwiches with peanut butter and bananas. It goes on smoothly and dries faster than regular spackle that’s diluted with water.

How important is it to use distilled water in thinning the spackle?

The Gesso additive is an interesting idea.  DAP lists Calcium Carbonate (limestone) as a major ingredient in spackle.

I wonder if you could mix in a little Calcium Sulfate (plaster of paris, Ag. gypsum) to adjust consistency for application and stiffness when hardened/cured?