Pressing decoration into foam, shaping and wire-brushing


Note this was originally a post from February 2013.

I couldn’t resist posting these results even though they’re hardly begun, because I’m pleased with them so far and wanted to at least make a brief record before I’m (as always) sidetracked into something else! I realized that, coincidentally, it has been exactly a year since I posted Making walls – Part 1 with the promise of a follow up .. so some attempt at continuity is long overdue!

decorated wall

I started working again on the two ‘wall’ examples here because I’m due to run my next ‘Scale Model-making’ course at Central Saint Martins and wanted to show some more evidence of what can be achieved with just Kapa-line foam. The wall structure above is pure invention or ‘architectural caprice’ with no particular style or period in mind, although it has turned out vaguely ‘ancient Greek/Egyptian’. The repeated decoration is very simply achieved .. using foam impression tools which in this case I’ve sliced from a set of plastic moulds used for cake decoration. I was only interested in parts of the shapes and in any case the complete shapes were too large to press into foam easily. The sliced details needed to be fixed (with hot-melt glue) onto wooden ‘push sticks’.

foam impression tools

I started the wall with the notion of giving it a heavy concave cornice but then decided to divide that into ‘teeth’ and to reflect those divisions in the rest of the wall.

building up wall decoration

These teeth (or ‘dentils’ as they’re referred to in classical architecture) are cut from the shaped strip using a try square to score an even line round and a long-bladed craft knife, as shown, to slice.

making dentils

The sides are neatened by sanding them against a right-angled sanding block.

sanding the sides

I use superglue to bond polyurethane foam parts together. Unlike other foams such as styrofoam the superglue doesn’t dissolve the surface, but it does soak in and start setting quickly (sometimes two attempts are needed). Superglues seem to vary and not all types work well with the Kapa-line polyurethane foam, but the best one I’ve found also happens to be the cheapest .. the ‘Extra Strong’ in tubes from Poundland!

wall in progress

Both the original cornice strip and the similar strip over the doorway were shaped using a sandpaper-covered dowel and the steps for doing this are worth noting.

setting up for sanding curved cornice strip

Above, I have sanded the edge of a piece of 10mm Kapa-line foamboard straight and perpendicular using the right-angled sanding tool shown earlier. I drew a pencil line to indicate the full width of the strip (i.e. not just the curved part). I then removed a strip of covering paper (by carefully slicing through the paper only and peeling away) exposing just the area to be sanded. Below, I’ve sliced away the corner along this strip, mainly so that the round sanding dowel will have something flat to start on.

chamfering edge

The sanding dowel is then dragged carefully against the edge, gradually creating and deepening the curve as it goes. With proper care a smooth, regular shape can be made in the foam fairly quickly. The edge of the paper covering left on acts as enough of a ‘stop’ for the sanding. Once this is done the strip can be sliced off to size (it’s usually better to extend the pencil line round to the back and cut halfway from both sides).

sanding a concave edge

Below is the other piece of wall I’ve been putting together at the same time, to represent the effect of old, sea-weathered wood which is achieved by dragging a wire brush firmly across the foam.

rough-hewn wall

For this I cut up some sample pieces I’d tried earlier, piecing together something less designed, more arbitrary looking. In this case I’ve basecoated the foam with a mix of raw umber acrylic and Paverpol, which gives it a much tougher/more durable surface without filling the detailed texture that much.

wire brush effect with foam

‘Making Walls’ will continue as a series ……..