The CNC forms that I had produced so far were quite rough despite using a very fine tooplath. I really needed the surfaces of Venus and Jupiter to be as smooth as possible because they are both going to be made in metal with a smooth and polished surface. I also want the ceramic pieces to have very smooth surfaces to reflect light evenly. With casting, the pieces you get out are only as good as the objects you are casting, therefore it is worth spending the time and effort getting the objects being cast as pristine as possible. It is also much harder and time consuming to cold work the surfaces of a material like Bronze, than smooth the surface in blue Styrofoam. I experimented with how much detail plaster picks up and how well the emulsion paint seals the surface of the blue foam by pouring some plaster onto some of the previous tests. You can see how much detail is picked up in the below images, reinforcing the idea that the surfaces need to be immaculate. I really like how the surfaces looked in the plaster though which was encouraging. The emulsion paint also sealed the surfaces of the foam very well with the plaster coming off without any additional releasing agent.
After successfully testing the use of Gesso mixed with PVA on the blue foam, I decided to continue to do further tests on some forms to find the best way of smoothing the surfaces as well as sealing them, as I wasn’t entirely happy with the surface from the sanded PVA/Gesso mixture as well as the amount of time it took. I experimented with sanding the blue foam itself with wet and dry which resulted in a really smooth finish which could then be painted onto. I then mixed the Gesso with emulsion paint to thicken it and help it fill in any holes, then painted this onto the surface.
I initially sanded this down with wet and dry to achieve a really smooth surface and polished that surface with wax. However, the wax reacted with the blue foam and in places where the paint was thin, the foam began to break down. The best method I found as a result of this, was polishing the surface using a wet cotton cloth after lighting sanding down the painted surface with a grade of wet and dry to initially smooth the surface. Below is the resulting surface which I am happy with.