I’ve just finished shaping my 6th board. The blank was a ‘second’ because of a couple of air bubbles in the foam. I was able to get rid of most of the worst of it through the shaping process, but there’s still a reasonably large dent in the bottom of the board, down near the front fins.
What’s the good oil on filling this in flush with the shaped foam? The sidelights make it look deeper than it actually is. It’s located within a concave, which is a pain, but nothing I won’t be able to overcome.
In the past I have mixed resin with foam dust and poured it into the hole, using a straight-edge to level it off. The problem with that method is that it adds weight, looks unsightly and creates issues with sanding, especially around the edges where it interacts with the softer foam.
I don’t really care about the weight and I can always disguise the repair with a decal. The issue for me is that it’s in the concave, which will make levelling it difficult, and finish-sanding it will be a minefield.
My first attempt at shaping was a fish-from-longboard project. The longboard was absolutely hammered which gave me the opportunity to fix several cavities of that magnitude. To be honest I tried a number of strategies with varied success. Spackle worked the best for me, including some holes at least that large. 5 years later, still no problems. I also tried mixing foam and resin but it was a mess to clean up becasue the resin was so much harder than the surrounding foam, plus it ended up a bit darker than the surrounding foam. I also tried shaping “plugs” and gluing them into the voids, but with my limited tool pallette, it was difficult to get an accurate fit when the cavities (like yours) weren’t on the rails where I could cut out a block of foam. (I tried to use gorilla glue but in retrospect, it might have worked better if I had used spackle as an adhesive/void filler.) good luck.
Here's an idea that might seem like a pain in the ass but will literally be an invisible repair....
Get some 'Fast & Final' spackle - the same stuff used to seal/prime EPS blanks - thinned with a little distilled water. Using a credit card, squeegee the 'F & F' in that hole until level. It might take a coat or three. Mask off your stringer with tape the exact same width. When dry, spackle the entire bottom with 'F & F.' When the whole thing is completely dry, sand the bottom lightly with drywall screen wrapped around a soft foam pad. Flip board and do the same on other side. A fine sanded spackle job is smooth as a baby's butt and you won't have ANY transition zones or gluelines as will be the case if you attempt to simply spot repair it. A smooth spackle job will also take paint perfectly evenly if you decide to color it.
If I were you I'd also do as Rooster says and use a mini-plane with the blade corners ground off to take off any of the high stringer.
Just after I took this photo I pulled out the block plane and gave that stringer a final pass. The sidelights really make the imperfections leap out, don’t they. Same thing with the deck, which I’ve also shaped a little concave into.
John, thanks for the advice, but you’re right, it does sound a little like a pain in the ass (or arse as we spell it down this side of the globe). Anyone who knows me knows that while I’m a big fan of quality, I’m by no means a perfectionist.
As to the stringer, I totally agree - see my previous response to Rooster. What I wouldn’t give for “a mini-plane with the blade corners ground off”… One can only work with the tools one has to hand, after all. Right now that’s a Stanley 110 block plane and a 60yo spokeshave. Suffice to say, stringer has been tamed.
Do any of the Australian Swaylockers out there know whether spackle is called spackle down here, or if not, what our equivalent to spackle is?
What can I say Ambrose, I just like to live on the edge, and I kind of like the thought of a dirty little 2yo handprint being immortalised underneath a layer of fibreglass.
Besides, I can’t glass it yet. I have to wait for 20L of resin to be delivered from the other side of the continent before I can get down to it. Just going to have to tiptoe around the shed until then…
John’s post about not thinning it is spot on. I’ve done several boards with big gouges. If you thin it, it’s going to take several layers and it will crack where it is the thickest. Thin it when you do the final layer to make the spackle flow smoothly.
If your plan is to sell the board, you better make it opaque, or do a fabric inlay.
I jumped the gun a bit when I said to thin the stuff with distilled water. You should fill the hole with unthinned spackle and thin it before you 'seal' the blank.
'Spackle' is a brand name for a product that is used for filling holes and cracks in plaster walls before painting. It is one of those names that has become used as a generic description of all similar products... like 'Kleenex.'
The thing about Fast & Final is that it uses microballoons as filler with an acrylic liquid base. One gallon of the stuff in a can feels like the can is empty. It is almost like shaving cream in consistency out of the can.
Anyone who has sealed an EPS blank would likely agree that it is no big deal smearing some spackle over a blank. It is used on EPS blanks to fill in any defects where beads have been removed during the shaping process and to prevent excess resin from soaking in to the blank.
It's not typically used on urethane foam blanks but it works. Some guys used to routinely seal the old Walker urethane blanks before glassing.
Lightweight spackle weights next to nothing, is white, cures in 4 hours, and you can glass right over it. Much lighter than any Q cell/resin combo and easier to work with, readily availible in 5 buck tubs at any hardware store.
I think I might have something like ‘spackle’ in the laundry, left over from when we painted the kitchen.
This one’s not for sale SC, it’s for me, so a clean finish would be nice, but isn’t imperative. I’ll try spackling and glass a decal over it to disguise any discolouration.