Stop Motion Animation Forum Archive











Posted by PsychoScream, on 2005-11-02 04:01:01

Cutting Polystyrene / Bulk Distributors

I'm going to make a set that involves polystyrene boards. How do I cut it? Can it be scored and snapped? What tools will I need? I'm assuming an X-Acto knife will be fine. Also: Does anybody know of an online distributer of inexpensive polystyrene boards? I'm looking for the cheap stuff in bulk. Both US and UK sellers are fine as long as they ship to the US. It's frustrating I can't find cheap polystyrene boards. I'd rather strengthen the stuff up myself with plaster coating and save money. I think GatorBoard is way overpriced when all I want is a freakin' slab of foam... Maybe I'm looking for the wrong type of foam board...? Polystyrene IS the kind of foam used for packing, isn't it?

Posted by m and j, on 2005-11-02 17:04:38

I know very little about this, however I will share my two cents. For actual sculpting hotknifes work great becasue they slice through the foam easily and you can create very detailed textures and shapes. You can check them out at Marc's site, here's the link As far as just cutting the foam to smaller squares or simple shapes, I don't know why just about anything sharp couldn't be used and then it could be sanded to a smoothe finish. Just make sure to wear a mask and goggles when cutting using either method cause I've heard the fumes and particles can be harmful. Anyone else that's more knowledgeable got some advice?

Posted by PsychoScream, on 2005-11-02 19:46:41

Have you tried sanding it successfully? If so, what grade of sandpaper did you use? Does anybody know what grade would work best?

Posted by Nick H, on 2005-11-02 20:22:54

I think you want big foam blocks, not boards with some kind of coating. (Foamcore is the thin board with a layer of styrene foam sandwiched between 2 layers of paper or card.) I get mine cut to size at a factory about 8 km away. The last lot I got was cut to 6 inches thick x 6 ft x 4 ft, a medium density with finer ball structure than the lightest cheapest low density foam. You have to add your own coating once you've carved it anyway, if you're not keeping it flat. If all you want is flat walls, particle board is stronger. I carve styrene foam with a kitchen knife that I sharpen on a belt sander, so it is very sharp but slightly jagged like a micro-finetoothed saw. I have to re-sharpen it frequently. Fine sandpaper doesn't do much on styrene, coarse is better. Try 60 to 100 grit. Hand sanding produces a fairly rough surface, power sanding seems to smooth it more. But I use it mainly for rocks, so the texture is good. Of course, hot wire cutting is the smoothest, it seems to seal the surface as it cuts.

Posted by Strider, on 2005-11-03 00:10:11

I'm not sure if this applies to the kind of foam you're talking about... this is for the carving foams or the insulation foams (which are pretty much the same thing)... but I've heard a good way to shape them is actually with a piece of denser foam! This would be after the initial cutting (which is often done with saws).

Posted by PsychoScream, on 2005-11-03 03:09:01

Custom foam cuts are very expensive around here...! I was interested in flat walls. For the price of a hot knife I can get a skill saw. Anyway, my local hardware store does custom cuts for free! I pay only for the requested size. It's stronger and cheaper than custom-cut foam. It looks like particle board is the answer. (That's my decision as of today's research.) Foam sculpting is beyond my ability right now. I think it would be easier to sculpt hardening clay AROUND foam shapes. The clay will stick, won't it? The foam would make the sculptures weigh less. If it works it will be more versatile/shapeable. I did find some basic foam shapes in different sizes for a cheap price. Maybe with a coat of something to make the clay stick better, and keep its moisture from soaking into the foam... Trust me, guys, you're not talking in vain. I'm writing this stuff down. Some of your advice may be used later rather than sooner, but it will be used! :-)

Posted by Strider, on 2005-11-03 04:19:49

Depends on what you're trying to make, and on how thick the outer shell will be. I've made setpieces from styrofoam rough-cut with a drywall saw and then I glue some burlap to it using Elmer's Carpenter's Wood Glue. Once that's dry, I slap on a coat of my beloved Durham's Rock-Hard Water Putty. Sort of like plaster but much stronger and it doesn't shrink as it dries. Oh, and it always works perfectly for me, which I can't say about plaster! A good deal more expensive too though. You can buy it through Ace Hardware stores... if they don't have it in stock just ask and they'll gladly put it on their next orde, or you can order through the Ace website. They'll either ship it directly to you (costs more) or to your nearest Ace store and notify you to go pick it up.