The material we all love to hate. It comes in such interesting shapes and sizes in the form of packing material and you can purchase it in sheets for very low prices in a large variety of thicknesses. However it also will make one hell of a mess if you try to cut it without a hotwire cutter. You can't use spray paints on it safely. On top of all that, it is probably one of the most fragile materials that we will work with when making terrain and scenics. I love the stuff.

First lets take a look at what we are dealing with.

Expanded polystyrene is basically made up of hundreds of thousands of little polystyrene beads, which is how it gets its more common name - beadboard. These beards which contain pentane are heated to cause them to expanded and then injected into a mold under heat and pressure to create the various shapes and sizes of items that we find today. The result of course is light weight, fairly study under compression and very cheap. In terms of packing material, you can get a lot of it for free - while the construction insulation will cost you less than a blister of minis or two trips to McDonalds.

So, what is to love about this? Well I used to hate it. I used to avoid it, and use only extruded foams. They cut much cleaner, tend to be stronger and hold up better when roughly handled. But then I had a bit of a eureka moment. While helping a friend winterize his house last year, I warned him about putting MEPS foam over the basement windows. I explained to him how the foam is actually quite porous and will soak water up from the ground and snow and hold it against the window frame, eventually leading to damage. It dawned on me then that this foam which I hated so much wasn't bad - it was just misunderstood.

Imagine if you will a bowl filled with marbles. While they take up a lot of the space whey also leave a lot of empty space. The MEPS foams are similar in many ways. Although the beads are heated up and pressed into a single sheet, you still have a lot of empty room in between the individual beads. What I have taken upon doing is filling that empty space with something stronger. Specifically water based acrylic varnish.

For obvious reasons the water based is important (if you would like to know more, place a Styrofoam cup in a tray filled with acetone or another solvent). The acrylic...mostly because it is cheap, and easily thinned out. When you coat the MEPS foam with the varnish it soaks down in between the beads and dries. The result is a honeycomb of acrylic reinforced with foam. Much like foam board the result is much stronger than either of the individual components alone.

Now it isn't perfect. You still will want to use a hotwire cutter most of the time you cut it. But most of the other problems related to the foam are taken care of. It becomes much stronger than extruded foams. You can spray it with spray paints quite readily without fear of it melting away on you. And it remains fairly cheap overall.