Modelling & Silicone Molds

        After our initial crit, the concern was raised about our two characters looking quite different. Fiona and I had hoped to reduce this issue by sculpting our character heads together, so that we could attempt to make them look as though they belonged to the same world. Unfortunately, this was not to be the case, as the pressures of various tasks meant I had to begin modelling without Fiona, while she finalised our storyboard and animatic.

        Due to the fact that the armatures would benefit from not bearing too much weight, we decided that foam latex would be the best material to create the heads from, as it is extremely lightweight, won't attract dirt like clay or plasticine, and can be painted. Another possible material we could have used would be silicone, to make a smooth outer skin. However, during my visit to Mackinnon & Saunders, they mentioned that they rarely use silicone as it will eventually degrade and fall apart. While this is unlikely to be an issue during our short shooting schedule, should I wish to reuse my character, it would be disappointing for the skin to have ruined. However, degradation is no doubt an issue with any material, as the oils from an animators hands can ruin latex with repeated handling.

        Bearing in mind what I had learned from the induction into molding and casting, I attempted to adapt my model accordingly. Rather than clay, which I don't get on very well with, I worked with plasticine, which I was told would work equally well, with the added benefit of not drying out and cracking. The texture in the hair had come through on my larger head, so I again used a clay tool to draw ridges to emulate swept back hair. The main change I made was to create the eyes from milliput, rather than integrating them into the plasticine model, which would hopefully allow me to change the direction of my character's gaze when animating.

        I also made sure to smooth down any joins between the head and the lips and eyebrows, as during the induction we were warned that these increased the risk of air bubbles in the casts, as well as it being likely that any features which were not securely attached would get stuck in the mold.

        Once I was happy with my character's head, I moved on to modelling the pigs. Judging from the story board, we would need a variety of different pigs, in different stages of the slaughter process. Although I had initially planned to create the pigs using Fimo clay, I changed my mind after considering that the majority of the pigs would need to hang from a rail. The heavier the pigs, the stronger the rail would need to be. The solution was to also cast the pigs in foam latex. Beneficially this meant that I could produce a vast number of pigs, but only model three (a live one, a hanging carcass, and a half carcass). As I am not the quickest at modelling, this would help me to be more efficient.

One of my modelling tools was the perfect shape for making the conical ears.

        I really enjoyed the modelling process, and the flexibility of the plasticine was a great help, as it was easy to smooth and rework areas which went wrong. The material adheres to itself far more readily than clay, and can be remodelled more readily than clay. The only downside I found to working with plasticine was when it came to making the molds.

        Don, the ceramics tutor, suggested that rather than plaster molds, I might experiment with silicone, which would potentially pick up a greater level of details from my models, and produce finer casts. However, it was important to ensure that my models had no noticeable scrapes or marks, as the silicone would no doubt pick up any unwanted blemishes. Before the silicone could be poured, I needed to prepare a frame to hold the liquid as it set, much the same as with the plaster mold during the induction. As silicone is quite an expensive material, however, it as in my interests to make the framework as tight to the model as possible to reduce costs. There still needed to be about 0.5-1 cm of silicone around the model. For awkwardly shaped models, a thickening agent can be added to the silicone, to cut down on unnecessary waste.

        Due to the nature of my designs, and the anatomy of pigs, quite a lot of weight needed supporting on relatively thin and delicate legs. This only became an issue when it was time to pour the silicone, as the pigs needed to stand, or be held upright as the silicone set around them. Unfortunately, the weight of the plasticine meant that some of the pigs have slightly skewed legs, but nothing too noticeable.

        As with the foam latex, the silicone needs mixing in the correct proportions if it is to work properly (a ratio of 10:1), before being stirred thoroughly and slowly poured over the models, giving any air bubbles the chance to escape. Once all of the models had been covered in silicone it needed time to set. This is a longer process than with plaster, taking up to about 5 hours

        The next stage was to cut open the molds. It was at this point that I realised I should have marked which was the front and the back of the mold, so I could judge where best to make the cut. This was not so much of an issue with the pigs, as they were all fairly central within their molds, but with Fiona's head in particular (we decided that I should take responsibility for all casting, allowing Fiona to get on with recording voice overs, finalising the big set pieces, and other tasks) it was impossible to judge which was front or back. Eventually I had to guess, and unfortunately the seam ended up cutting right across her character's face. Luckily, the foam cast still came out well, albeit with a slight coating of plasticine where some of her original model had stuck. 

        To ensure that it was easy to fit the two halves of the mold back together, I was advised to cut some zig zagged edges, which would fit together like a jigsaw. In future, I could also leave one side uncut. For some details, such as the ears, additional cuts had to be made to make these easier to release.

        While the silicone created a smoother mold than the plaster, the first couple of foam casts still stuck to the mold a little. Rather than use the waxy mold release, which left a lot of residue in the more delicate and detailed molds, Don suggested a thin layer of vaseline would prevent the foam sticking. By reapplying a little vaseline after every two casts, I managed to achieve some good results.

        Don had also expressed some concerns before I began casting that the tails and ears would prove too delicate to cast. This seemed to be the case at first, as the first pig came out with neither ears nor tail. However, by ensuring that I held the mold at the correct angle to flow into these extremities, all subsequent pigs had ears and most of a tail (this same problem occurred with the legs on some of the hanging carcasses). There were however, persistent air bubbles in the pigs' stomachs and beneath their chins which I was unable to get rid of, as to turn the mould to allow the air to escape would also cause the foam to pour back out. Fortunately, we were not planning to film the pigs from an angle where this would be noticeable.

        While the casts I produced are perfectly good for this project, the consistency of the foam could have been finer. Some of the pigs have very large foam cells in their backs, and the faces are quite pockmarked. This is most likely because my stirring of the foam introduced large amounts of bubbles to the mix. Some instructions which Don found recommend using an electric mixer to achieve the best consistency. However, painting the heads with liquid latex mixed with acrylic paint should help to give the characters a smoother complexion.