Kapa-line foamboard (the ‘peelable’ type with the cream-coloured foam inside which I’m forever recommending for a wide variety of surface effects) doesn’t come cheap and it’s only available from a handful of suppliers. See my page Updated sources/prices for specific materials in the Suppliers section for current prices
Recently, having long been aware of these ‘practical drawbacks’ I tried again to investigate possible alternatives. I remembered that I’d been able to peel the paper off certain kinds of black foamboard in the past but had never tried to create surfaces with them. I spent a morning and came up with some quite positive results! I had a number of old scraps of 5mm black foamboard, some noticeably different from others. The paper covering could be peeled from some, but not all .. I’ll come back to that later!
Above are some tests being made on small samples of foamboard with the paper peeled off. Sometimes the paper comes off quite easily and the foam surface remains fairly smooth and unmarked. Sometimes removing the paper rips up the foam slightly but this can also create an interesting surface. Acrylic gesso binds well with the foam surface as do all the acrylics I’ve tried (the bottom sample is a very light coat, while the top shows a heavier one). Also at the bottom is a brickwork pattern just started, beginning with the horizontal lines (just inscribed with a mechanical ‘push-lead’ pencil).
One thing I’ve found is that the bottle acrylics (such as DecoArt, Inscribe etc.) tend to be more opaque than regular tube acrylics (such as System3). This makes them better suited for these heavier dry-brushing effects, unless you want the black to keep showing through. Above, I’ve broken up the brickwork pattern by scraping with the tip of a scalpel and pressing the foam in places. I haven’t even bothered to painstakingly include the vertical brick divisions. I depends what level of realism you want, but I don’t think it’s always necessary. Below is an additional sample in which I’ve just patterned portions of the foam surface as brick and left others flat which are then gesso’d.
Another recent discovery I made when experimenting with the denser Kapa-line foam was the heavy woody effect which can be made by firmly dragging a wire brush along it a few times. As you can see below this works perhaps even better with the cheaper black foamboard. I wouldn’t recommend this if you were trying to model fine interior floorboards but it’s exactly right for rough, worn or weathered timber. The sample on the right has been skimmed over with raw umber and light grey acrylic.
Now to the slight problem! I mentioned that the paper can be peeled from some types of black foamboard but not all. I can’t tell you which will work simply by brand name because most often what you find is ‘unbranded’ in that, as far as the shop is concerned, ‘black foamboard’ is enough of a name and they don’t know or particularly care about where it comes from. All I can say for the moment is that if the 5mm foamboard you find is a tiny bit less than 5mm thick and the foam edge is slightly greyish then it’s likely to work. On the other hand there’s a type that is very slightly more than 5mm thick with a darker, less dense, more ‘glistening’ foam edge and this is not likely to work. If I find out more I’ll post it here!
Where to get black foamboard
Here there isn’t much need for a list of suppliers because it’s likely to be stocked in almost all art/craft or graphics shops. In London I usually get mine, a little discounted, from University of the Arts (UAL) college shops, currently £6.55 for an A1 sheet (November 2014). These shops aren’t open to the public anymore, but the 4D modelshop or the Paperchase ‘flagship’ in Tottenham Court Rd sell it at fairly standard prices .. around £6-7. As I’ve said, these are likely to be different brands and there will never be any guarantee that one will behave exactly as another. The only ‘branded’ black foamboard I’ve come across has been either Westfoam (4D modelshop and online) or Frisk Biodegradable Foam Board (online). The Frisk type has worked very well when I’ve tried it in the past but it’s more expensive than Kapa even .. currently on amazon.co.uk costing £12 for a pack of just two A2 sheets!
Using heat gun or hair-drier on foamboard to assist removal of the paper does work! Finally I’ve had a chance to test the advice that ‘davie’ posted here earlier in the year using a small heat gun and it worked remarkably well as soon as I’d got the knack of ‘heat ‘n’ pull’ in stages! The heat melts the bond between the foam and the paper but these very quickly re-bond on cooling so the best way is to start by loosening just a corner, peeling up, and then progressing in diagonal strips until reaching the opposite corner. Keep the hot air away from the exposed foam if using a heat gun because although polystyrene will withstand the heat of hot coffee it will shrivel under a heat gun, though hopefully not under a hair-drier!
I tested this during a recent model-making course, so the students had an opportunity to try and they managed it fairly well. Although I didn’t see this, one of them told me that she’d peeled a small piece just by breathing on it in stages! .. I believe her, but I really have to try this for myself. For this course we were using black foamboard bought at the Central Saint Martins (UAL) college shop. Although this is ‘unbranded’ I’m pretty sure that this is supplied by the wholesale supplier Seawhite of Brighton, but where they get it from I don’t know. I noticed for the first time with this foamboard that the two paper covering layers have slightly different thicknesses and that the thicker side was easier to remove, even carefully by hand without the assistance of heat.
There is quite a lot on web forums dealing with different ways of removing paper from polystyrene-core foamboard .. including soaking in hot water, even using other solvents .. which one can find using a search terms ‘peeling’ or ‘removing paper from foam board’ for example. Most of this info comes from the flown model aircraft ‘community’.