I’ve had a few requests for more information on how I worked on the polystyrene armature for The Singer, so rather give an individual response, I thought I would post a bit more detail on the process on this blog.
The writer wanted me to provide a list of processes to go through; for instance, did I start with the back, front or sides? The first thing I have to make clear is that I do not have a clear & simple formula for cutting a polystyrene armature. I can just describe what I did. If there are any more specific questions I can try to answer them.
As outlined in previous posts, I started with a maquette and my goal was to reproduce the maquette in a piece of polystyrene at a scale of 1″ = 4.5″. I began by drawing the x & y axis onto the base of the maquette with 1/2″ numbered intervals. I then create a vertical z axis measure as shown in an earlier post. Then as shown in that post, I marked off the x & y axis on the wooden base of the polystyrene piece at 2.25″ intervals and numbered them the same as on the maquette. Then I created a vertical Z axis measure with the same numbered intervals for the large scale. This was the easy part.
The hard part was actually transcribing the measurements form the maquette to the final work. This system is more designed for an additive process like clay, when the artist can build the clay up to the point indicated by the measuring devices. With a reductive process like carving, the problem is that the point you want to get to is inside the block of material and figuring out how much & where to cut in order to reach that point is very difficult. I managed to cut away too much and had to glue more polystyrene back on. If you look carefully at the images in the same post you can see lots of yellow repair sites .(Speaking of glue, the best glue is that Expanding Spray Foam Sealant. It expands to fill the space so you don’t have to cut the amended piece exactly to size. Actual styrofoam glues form hard lumps that are too hard to run a hot wire through & are a huge pain.)
In order to record the location of reference points (such as the top of shoulder, bottom of elbow, top of knee, frontmost point of shin etc. ) I would measure it on the maquette and write down its numbers on the x,y & z axes. I started with the front and worked from the top to the bottom, then did the back. I would find a reference point on the polystyrene, mark it with a pen, connect the dots, and draw the outline. Then using the hot-wire, I cut off large swathes of polystyrene to create the very rough general shapes of the back & front. Then I did the same thing with the sides. As shown in another earlier post by that point I had the general squarish contours of the shape.
Here is where miscalculations caused later problems. The hot wire heats & stretches, creating a curve so that you are cutting not a flat plane but a concave surface. So my advice is to err on the side of caution when doing the initial big cuts. The process from there was one of going back & forth from the maquette to the polystyrene, measuring & marking points on the x,y & z axes and gradually whittling down this large squarish shape into a more rounded shape and carving in the more detailed forms. It was not easy and took considerable time, labour, concentration & organization.
I made jigs to hold measuring devices (squares, triangles, rulers) and a level together to make sure I was measuring accurately. As the reduction of the block progressed, I found the hot-wire was too broad to use and it can’t do indentations. So as I also discussed in that post I used a sawsall and a disk grinder to do more detailed work and a hand-held keyhole saw to do the fiddly bits. Here is the armature for The Singer as of now. I will complete it when I have a home for the final work. This will entail reducing the form so that it is 3″ smaller than the desired final size to serve as an armature for concrete or plaster added to the surface.
The whole process was very labour intensive and I would love to have had the money to be able to just send my maquette to one of the CNC shops and have them scale it up to full size for me. But as this was my own experiment for my own interest and no one was paying me, I had to do it the hard way.
Cutting polystyrene is hard, unpleasant work, especially when I got down near the floor and had to work with the sawsall in a crouch. Wearing a mask against dust & ear protection against noise is tiresome, so for a break I have been working on other projects.
As a pleasant and easy task, I am making molds and casting the plaster maquette of the singer.
I began by creating a polyurethane rubber mold, using Smooth-On’s Brush-on 40 product. They have a great video on their site explaining the process, though I wish they would choose a more challenging shape than a human head. Here is the rubber mold:
Then I made a mother mold out of plaster, instead of using Smooth-On’s recommended product, Plasti-Paste because I happened to have an old bag of lumpy Plaster of Paris in the studio. Big Mistake!! The plaster had been sitting absorbing water in my unheated studio for a couple of years & did not work! My advice – always go out & buy fresh plaster. Old damp plaster is clapped out & no longer reacts with water so the result is a crumbly mess. So a brand-new bag of P of P later, the mother mold took proper shape.
Once the mother mold hardened, both molds were removed, re-assembled without the original and placed upside down in a bucket for casting. I cast a few copies in hydrostone & a few in concrete, with varying results. Hydrostone is tricky to work with as it remains liquid for a long time while mixing then suddenly sets up leaving almost no time to pour. You have to pour before it starts to thicken or you’re done for.
To be honest, I had to patch up a few holes & sand them smooth again.
I also experimented with casting in concrete.