The ingredients that are added to make the paint flow all require high water contents and this gives longer drying times. Thick paint does not necessarily mean it has got more pigment in. There are some of the cellulose thickeners where you can put one-and-a-half or two percent in water and produce a thick jelly. Polycel, for example, is a cellulose. Household emulsion paints are thick because they contain a cellulose rather than lots of pigment. There are dozens of different sorts of celluloses on the market for use in all kinds of products. For instance, these cheap children’s puddings in a little plastic pot, they may have 2% powdered milk, 1% chocolate, 1% sugar, a lot of water and a bit of cellulose thickener and they come out as nice solid spoony things. Celluloses are used through out the whole food industry. Not exactly the same ones that I use, some are used for foods, some are used for medical purposes, making ointments, creams, that sort of thing. Some celluloses have very high water absorption and so it takes a lot of liquid to get adequate flow. I have always used combinations of thickeners, which will give the flow without the high water demand. I have always used combinations of thickeners, which will give the flow without the high water demand.
If you paint ordinary poster paint onto a cel it does not take very well. There are two reasons for this, one is that ordinary poster paint uses a gum to bind the pigment, the very rough and absorbent surface of the paper will provide sufficient key so that it wont flake off. When it is going on to a cel that has a very smooth surface, there is no key for it, so it will fall of. The other factor is the wetting. When you apply a liquid, such as water, to an oily surface it will just go in little bobbles, it won’t actually wet the surface. In the water based polymer paints it is necessary to use wetting agents for a number of reasons; you use wetting agents to wet the pigment and you use wetting agents to wet the surface. I use a wetting agent that is particularly good at wetting cellulose acetate, triacetate and diacetate. I tried lots of different wetting agents before I found one that wetted the cel very well. It is a totally “suck it and see” process. I have talked to many paint chemists in technical departments all over the country and abroad as well. You ask them a question and they say “Well, it’s very hard you know. We could always do a little trial work for you”. Or “All I can suggest is that I send you some samples and you see which one works the best”. It is always like this all the way along the line.
With regard to applying the paint to cel, the paint is a material thing that the painter has to come to terms with and understand the way in which it behaves. It is difficult to say how much water should be added to each colour to get the right flow characteristics because each ingredient that goes into the different colours varies. The painter should put a small amount of paint into a little mixing vessel and then add enough water, gently stirring with the brush, in such a way as to fold the water in, rather than whisk it as if they were making an omelette. Fold the water in until the paint is the consistency of thin cream. They should even have a little piece of cel beside them and try out the paint they’ve diluted just to see if it is flowing properly. If it’s flowing too freely then it’s a little bit more paint, if it’s not flowing freely enough then it’s a little more water. Once they have got the right for that batch of paint they’ve mixed up then they can put a lid on that and keep it. I could produce a paint that is diluted to the optimum level for use directly out of the bottle except that people would just be paying good money for 20% water, or 25% water. Cartoon Colour’s Cel Vinyl comes in the state in which you use it, you don’t dilute cel vinyl, you just give it a shake up, and it’s very runny. When one is looking at a price for paint one has got to take that into account. A 1200 cc pot of my paint, when diluted down, is going to be in excess of one-and-a-half litres.
The technique for painting cels is that you then put a big blob of paint in the middle and flood towards the outline. When the area is painted the appearance should be of a more or less flat, uniform sheet of paint over the top of the cel. It shouldn’t have great blobs in it. If the paint is used very thick, you sometimes introduce little bubbles during the mixing up of the paint. Many people think that these are actually lumps of something but they are not. Because the viscosity of the paint is so high the bubbles haven’t got enough buoyancy to float themselves out. On drying, even paint straight out of the pot will usually loose all of its bubbles because as the water evaporates the thickness of the film goes down, the bubble manifests itself and pops.
Printed in Animator Issue 13 (Summer 1985)