Cutting Insolation foam

I have had really bad luck cutting this stuff and have thus given up on it all together untill such a time that I can find a reasonable and cheap means to cut it.
I have tried a saw (wood, hack, and electric) to no avail, I have also tried a kitchen knife (don't tell my wife), and exacto knife.
nothing has worked for me to get "clean" edges... though the electric saw had the best results.

So I ask what should I use?

And well i'm here I know painting it with spray paint (primmer) is out, so what do I do to give it a nice under coat?

What thickness do you use? 1" is easily cut with a razor blade, and then sandpapered down to a smooth finish if you use a fine grain paper. You can also score with a razor blade halfway, and then break the foam off to get a decent finish as well, and then trim it with the razor and sandpaper. As for an undercoat I use a slightly watered down black acrylic paint, the cheapest I can find as it mostly soaks into the foam the first time around.

I have been cutting mine today with an electric jigsaw, and its worked a treat.

I have had poor luck finding 1". I think I ended up with 2" as the only workable size I could find. For some reaon the hardware stores around here don't carry it any smaller (unless it's the supper thin like card board).
Hence the bad luck with the razer blade as it isn't long enough to even come in from two sides.
I can hunt more for 1" though.
Never thought to use sand paper, don't ask why

Paint: Thx will try

I got a jig saw, I didn't try that saw so I will try that this weekend.

I used to have to use the 2" foam all the time when I worked at the opera house making scenery back in college. It is easily cut with a jigsaw or tablesaw. Just be careful if you are using any kind of handheld saw as the foam has a tendency to move and wobble. I also think you can use one of those hot wire cutters that GW used to sell a while back, but I can't remember what they were officially called or where you can get one. Sandpaper is the easiest way to smooth the surface from a rough cut, if you use a rough grain you can quickly remove the foam to shape it too. Just make sure you do it somewhere you can make a mess, because the foam bits that you sand off will get everywhere and tend to fly all over the place.

You can also use the razor blade to score halfway through the foam, and then punch it to break it out. This is a very fast way to cut straight lines, but isn't as accurate as cutting straight through. I wouldn't recommend it for detail work, but for quickly breaking it down to size the foam easily splits in half with a scored cut.

I Use a woodland scenics hot wire cutter ( Review can be found here )



I used to have one of the GW ones, but as it was battery powered, the costs soom started mounting up. the woodland scenic one is mains powered.

I've always used those cheap box cutter knives. Just slide the blade out to full length (3 inches or so) and gently saw along. You go through quite a few since it dulls the blade quickly, but they're usually five for a quid so it's not really an issue.

I use the box cutter, various saws, & hot wire tools. A saw with a saber saw style blade works well with thicker foam. For a very smooth cut on thinner foam just heat the blade over a candle for 10 seconds or so & use a ruler to guide the cut.
The saws can leave a nice rough texture to a piece or you can sand it down . Fine or medium grit sand paper leave a smooth finish while coarse/very coarse is good for texture.
If you've got a few extra $s the Hot Wire Foam Factory tools are FANTASTIC:

http://hotwirefoamfactory.com/home.php

I use fire, an old wooden handled dinner knife and oven gloves.

works a treat - but you need lots of open doors/windows

I use this material quite often for my work (building theater scenery). My advice is just echoing what others have said here.

Partially it will depend on what you're cutting it for. Buildings with a straight edge? The table saw is the best way to go, but please be careful. A bandsaw works wonderfully for cutting curvy circles and hill shapes. A jigsaw (saber saw) should work pretty well as long as you've got a nice sharp blade.

A router also works well for cutting and carving, as long as you've got a decent jig. I've made 12" wide 10' diameter circles out of laminated overlapping sheets, and a router on a stick was the only tool used.

I'm also quite lucky in that my workplace has one of these: Original Foam Cutter by Riema It is Deluxe. I cant imagine you'd shell out $200 for one, let alone $500 for the fully kitted out set, but it's a fantastic tool.

I'm a much bigger fan of this knife style foam cutter than the bow style cutters, but they both have different applications.

I've used this knife for making hills and caverns for my minis and just love it.


If you don't have a wood shop, however, let alone a scenery shop, a hobby knife should work well. The trick is to not press too hard. take multiple passes. Trying to cut all the way through will rip the foam and give you crappy edges.

The material is typically intended for insulation in houses, so it's rare to find it in less than 2'x8' sheets, or even 4'x8'

A hardware shop might be able to cut it into more manageable sizes though with their tools, e.g. 2'x2', if you ask them.

It does however sand quite nicely and smoothly. Sandpaper will get you there, although a light touch with an electric palm sander or maybe a hobby dremel would speed things up. We've made full sets of snowscapes before out of the stuff, with lots of sloping curves.

Be careful of the particulate dust, try and work outside. Your wife will thank you. And if you use any kind of hot tool, definitely work outside or in a well ventilated space. The fumes are not at all good for you and you will feel it.

A couple quick words about gluing? (as though i haven't ranted long enough) The ideal for foam is a two part contact adhesive. I don't remember brand names off hand, but the stuff is awesome. We use it at work for applying foam to walls, etc. However, for light use.... wood glue or white glue will actually work. It takes a long time to dry, because there is very little airflow in between the materials.

A speedier and smellier alternative, is to use a spray adhesive. In the states the kind i've used is called spray 77. (spray 90 is a heavier duty version). If you use a very light coat on both faces, it won't eat into the foam and you can get a really good fast stick. if you spray too heavy, the thing will just disintegrate in a pile of nasty fumes.


As mentioned the same is true of spray primers. The acetone in spray cans will dissolve pink , blue and bead foam. Acrylic or even latex (house paint) is your friend.

If you've got a ton to do, you can find a pump sprayer (hudson sprayer) use thinned and filtered latex paint . Brushing it on might be just as fast....


That's my input... hope its not too unclear....

I usually don't have any problems with the stuff, but lately I have been trying to cut 2" wide strips out of the 2" thick board with nice, clean edges. So far I have had little success with a utility knife.

Even with multiple light passes and a straight edge, I have been having a tough time keeping the cut perpendicular. I'm going to give it a go on a table saw and see if that works.

Like Si, I've allways just used a cheap box cutter knife. The trick is to hold the knife at an angle and go for several passes. It ripples easily, so a light first cut is important. It's easier to achieve a perpendicular cut if you place your body and head above the line you're cutting.

I have the same problem.

I've been trying a LOT of foam types and for the life of me, I cant cut any of them. Cut them nicely and tidily, that's it.

I keep seeing foam buildings here and I can only shake my head. I don't know how you guys can work with foam this way

P.S. Newbie here! What a GREAT place this forum is.

Ive been messing about with foam for the last few weeks and started to get a good idea on how to use the stuff, as for spraying it with primer I always give the foam a basecoat.

The best basecoat ive found is 1:1 PVA:Polyfilla, with a dab of water to help spread and mix. The reason for this is that the combination really sticks to the foam well and sprads on easily with a brush. Pollyfilla by itself is unwieldly to apply as its too thick and PVA has a habbit of not covering very well.

Im using this for bricks and stone walls as it gives a natural look but will hide detail on statues and wont be perfectly flat so doesnt apply to 'Elven' style scenery. Works for Mordheim though!

Another tip is using superglue on Styrofoam melts it, but not that much its great to spread a bit on for a really weathered effect, acid corrosion or something similar. Hope that helps!