I would like to take most or all of the concave out of one of my surfboards. Finding foam to fill the void and then shaving it sounds a bit too
involved and I think it might not work until I have more experience with foam, planers, etc…
So I think pour foam might do it - similar to what a boat-builder sometimes does to fill in voids and surfaces before glassing with resin.
Just curious if anyone has ever tried this and will it work?
I want to just buy some pour foam (probably 16lb. density), then pour it in (I guess followed by the activator). Then just toss a piece of plywood over it to
keep it weighted down and to make it come out nice. Then I can either go flat or put a slight concave back into it, less than the original. I just want to know - will this basic approach work? Will the plywood lift up - should I weight the plywood down? Should I put a little vegetable/olive oil/surfboard wax on the plywood to help it pull up more easily so it doesn’t cause voids in the foam? How long will it be before I can put the sheet of glass/resin over it to finish the job?
So questions are:
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Good idea?
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Which vendor - Fiberglass Supply Co. (8lbs) or US Composites (16 lbs - and do they have only a pint size?). I don’t want a quart or gallon of this stuff.
As for an exact product - I will need something that is marine-grade (water contact won’t harm it). For example, Fiberglass supply has 8lb density pint:
8 lb. Density Pour Foam Kit, a two component, 8lb/cu.ft. density rigid hard-skinning polyurethane pour foam. Use for filling voids, tooling, molding and taxidermy. Mixing Ratio A/B by weight 50/50.
K08-8321 2 Pint Kit, 8 lb. Density Pour Foam (A + B) 2.3 lbs. = Approx: .27 cu. ft. It costs $35.19
3) How much liquid will I need? Expanded, very roughly I will need about 1/4 in. x 2 ft. x 6 ft./2, /2 since it's less at the sides = 1/48 ft. x 2 ft. x 6 ft. /2 = 6/48 cu. ft. This is a very rough estimate based on the volume of the concave that I want to fill.
So does anyone know how much of my 35.19 I will use up? If it's not too much, then I'm not worried. How much will the liquid expand?
4) Should I protect the surfboard's bottom or coat the bottom with anything first?
5) I realize that Jamestown Distributors has little 1" thick sheets of foam that are 1' square for like 9.95 a block. So is there foam hard enough? I thought of the pour foam idea because I am so worried that I'm going to order from Jamestown or some distributor and wind up with foam that came off of a roll and it's
not stiff and it's for seat cushions or something. I NEED closed-cell, stiff, marine-grade polyurethane foam and it must be good stuff. I don't want something
that's junk.
Well anyway, if anyone can guide me a bit, I've never used pour foam. And if I were to buy the foam from Jamestown, I would need to get a bench grinder and sharpen my hand-planers. I have not yet bought a power-planer.
I really don't want to spend a whole lot of money.
I guess there are other void-fill methods I could use, but I like the idea of putting foam in there and glassing over. But perhaps there are other void-fill
materials other than foam. I could use cabosil/resin but it's an awful lot of weight and perhaps cost. But at least it would work fine.
So my last question is:
6) Should I not use pour foam, and just add a little too much weight with the cabosil? It's a lot of cabosil though - it was perhaps a reject surfboard - the concave is WAY too deep - like 1/4" or more.
Anyway, any comments appreciated - no hurry.
Thanks.
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