How do you make foam?

I'm trying to figure out how to make a surfboard without sanding down a foam blank, because blanks are expensive and I'd much rather pour something into a mold shaped like a surfboard. I don't want to have to buy the kits to pour foam because they're also pretty expensive for the scale that I'm talking about. I guess what I'm really asking is how do you make the two liquids that are in the kits to pour your own foam?

kidofBMX1245 years ago
Making a surfboard requires a degree sanding and a bit of shaping regardless. Depending on the size of the board you wish to make you can buy a EPS blank for around $60 and figure in shipping. Another avenue you can take is go to your local hardware store and buy a few sheets of rigid insulation foam and a can of Great Stuff and laminate the sheets together to make yourself a blank and then go from there. Good luck!
Prfesser6 years ago
I don't know anything about surfboards but have made a good many tubes from fiberglass and epoxy resin and have used polyurethane foam to fill various parts.

First, you cannot make the two-part polyurethane foam components, it's WAAAAYYY too expensive.  One part is a carefully-formulated di-isocyanate, the other is a carefully-formulated polyol that (usually) has a measured amount of water in it.  The diisocyanate reacts with the water to produce CO2 gas that makes the foam.  I teach chemistry for a living but would not even attempt to make my own 2-part foam.  I buy it....

That being said, to make a large relatively-flat surface like a surfboard, I would consider using the sheets of *extruded* (blue or pink) styrofoam.  It's solid foam, not like the "beadboard" that's made of tiny beads.  It's quite cheap, about $12 for a 1" sheet 4x8 feet. To make the mild curve I'd "stack" foam near the ends (glue together with a thin layer of epoxy) to build up the thickness, then carve or sand away the excess.  rickharris is right, sanding foam is very quick, especially with a power tool.  A drum that chucks into a hand drill does a pretty good job.  But do it outside as the dust is a real mess!

Good luck!
rickharris6 years ago
Harder to make the mould than sand down the blank.

The mould has to be hollow. It's surface has to be mirror perfect or the finished blank will be imperfect and need sanding, that's where we came in.

The mould would need to withstand pressure and be able to be split to remove the blank. All that for one use only.

Sanding foam is really quick and relatively easy. Most of the extra is cut off with a hot wire.

As for the chemicals they are going to cost you as much or more than the 2 part kits because you only want a relativly small quantity.


gives you the chemistry.
+1. MUCH easier to sand than mould - and vastly cheaper.