The first thing to do is to get a foam sheet of the desired size. The advantage of this method is that we can define the thickness of our foamboard as we want. Foam is usually available in blocks much thicker than 5mm, so we will need to make thin sheets for our foamboard. For this I use
my hot wire cutter, so I get sheets of the desired thickness. With a little practice and patience you get almost perfect results. As I have been able to appreciate, to obtain a 5mm thickness foamboard, it is necessary a core of foam of 4mm. The two layers of paper and glue add up to approximately 1mm. After passing the hot wire, it is advisable to sand with fine sandpaper to achieve a smoother surface. This step is optional but greatly improves the final result.
Once the foam core is ready, we mark it on the paper we will use to cover it, letting at least 1cm extra. In my case I used for tests, sheets of office paper, so I have a size limitation. But you can make pieces as big as the paper you can get. We will remember to make 2 layers of paper one for each side.
Let's get started
Making homemade foamboard is not difficult, from this point one could think of using aerosol glue to attach the paper to the foam core. Excellent, if you thought about it, you have discovered one of the ways to do it. But what if where you live you don't have access to aerosol glue as hard as it may seem? There are other solutions for this.
One solution is to use white glue mixed with water 50-50%. But we can also use much cheaper and more affordable materials to make homemade glue. The glue I used in my experiments is made with water and wheat flour. Yes, wheatpaste is cheap, simple and super strong. I could do a whole wheatpaste tutorial, but I have found this excellent
instructable that perfectly describes the process. Just to make it clear that in my experiments i didn't use any additive and instead of cooking the mixture directly in a pan I preferred to do it in a bain-marie mixing constantly until obtaining a watery consistency.
Step 1
Laying the foam sheet on a flat and protected surface, apply the glue all over the surface using a medium brush. Then remove the excess glue using an old credit card.
Step 2
Take one of the layers of paper, sprinkle it with water and put it on the foam sheet. With care to not tear the paper, remove all bubbles and wrinkles using the credit card once more time. If necessary, pin the bubbles to let the air out more easily.
Step 3
Once the paper is completely fixed, apply a new layer of glue using the brush and removing the excess with the credit card trying to leave a flat surface.
Step 4
Have finished with one side, then turn and repeat the process for the other side of the sheet.
Step 5
When finished, will hang it and let it dry in a ventilated place but avoiding the direct sun light. The direct sun would produce a differentiated drying of the layers and could produce some deformations.
