Foamcore Techniques

Foamcore consists of a piece of foam sandwiched between two sheets of stiff paper. The result is a lightweight board favoured by many terrain makers for the construction of buildings. Foamcore, also know as foamboard and artboard, is usually quite easy to obtain from model shops, craft shops, art supplies stockists and stationers. It comes in various colours and thicknesses however the most common, and probably the most useful, is the 5mm white board.

Foamcore is easy to cut with a craft knife but you should not attempt to cut right through it in one pass. Using a steel ruler as a guide, slice through the top layer of paper, cut through the foam with a second pass, and through the bottom layer with a third. Working this way, in a controlled manner, will result in clean, square cuts. Note that a sharp knife is essential to avoids tearing of the foam.

The simplest method of construction is just stick the sheets together however this results in a 'seam' of foam being visible at the corners. If the construction is to be coated in spackle, this is not a problem however if it is to be painted, and foamcore is ideal for this purpose, this is easily dealt with, for 90 degree corners, by cutting a rabbet. Although they are commercially available, it is relatively simple to make your own rabbet cutter, or you can cut them with a craft knife.

The images below, supplied by Iceworld Ray, illustrate the process:

The first step is to use a couple of spare pieces of foamcore to mark the width of the rabbet on the piece to be cut. The next step (not shown) is to use a craft knife and steel rule to cut through the top layer of paper. A second pass cuts through the foam taking care not to cut through the bottom layer of paper. The sliver of foam and paper is then cut away and the piece is ready to be glued.

For corners other than 90 degree angles, on a hexagonal shaped bunker for example, you will need to cut a mitre. Once again, commercial cutters are avilable but note that to get an accurate cut, you would need a different cutter (or one on which the angle can be adjusted) for each different angle that you want to cut. Before you rush out to the shops, bear in mind that for most terrain makers, this is not an issue as we are usually only concerned with what the piece looks like on the outside. Thus you could build a hexagonal bunker with 45 degree mitres - there will be gaps on the inside but you can fill them and they won't be seen when the roof goes on.

PVA is ideal for gluing foamcore. Other adhesives, especially those intended for paper and card, can be used but avoid solvents and/or heat which will have an adverse affect on the foam. Note that the foamcore will usually need to be held in place with masking tape or dressmakers pins while the glue dries.

The foam also needs to be taken into consideration when painting. Depending on the nature of the building it may be possible to hide all of the foam edges however any that are exposed will require extra attention. The solvents on paints such as spray primer will eat into the foam so any exposed foam should be coated with water based paint or PVA before spraying. In some cases this may be enough. The photo to the right shows a building by Neal Crankshaw where Neal has chosen to 'use' the edge of the foamcore rather than try to hide it. The result looks like a wall that has cement rendering on the outside and plaster on the inside. Neal has also used foamcore for the floors and inserted lengths of rust coloured wire to give the effect or reinforcing bar poking out of broken concrete. A very simple and effective piece of detailing.

When Neal wants to hide the edge of foamcore, as with the butresses on his control bunker (below), he sticks masking tape to the exposed edge and trims it with a craft knife.</a>

Another useful technique with foamcore is to peel away one of the layers of paper to expose the foam; a task which Longshanks suggests is made easier if you wet the paper with a damp sponge. Ariss removes one of the paper layers to create some amazing looking paved stone floors and the photos below, by Maffo, show the technique in use to create a war torn bunker. Note that the exposed foam needs sealing with PVA before spraying with primer.

Check out http://www.maffo-models.com for more of Maffo's terrain.