Paints. Your choice of paint can have a big impact on your modelling. Acrylics, lacquers and enamels all behave differently, need different materials for thinning and clean-up, have different drying times, and react differently with other paints and other chemicals (such as glue). Research your paints and decide what’s right for you. Acrylics are water based, so they are easier to thin, easier to paint with, generate less fumes, dry faster and clean up easier. Enamels are thicker, need stronger thinners, are less forgiving to paint with, generate dangerous toxic fumes and take longer to dry. But they are more hard wearing and are affected less by other chemicals.
Understanding how paint “works” can help you get a better result. Paint contains two main components: Pigment and a carrier. Pigment is what generates the colour, while the carrier is what makes the paint a liquid. When you buy paint, the instructions say to stir or shake it well before use. This is because the pigment will settle to the bottom, and you’ll end up with a very thin paint on top, with a glob of pigment on the bottom. Shake your paint very well for 1 minute before opening and then stir it well to mix the pigment and carrier, and to prevent lumps.
Priming. To prime or not to prime, that is the question. Officially, you generally shouldn’t need to prime your models before painting. When the parts trees come out of the mould, they have a release agent on them which will prevent paint from sticking. You can wash the parts in warm, soapy water and allow to air dry, then paint without priming. Priming will assist the paint to adhere to parts, and can be applied without washing the parts first. Primers can be expensive and, since they are not 100% essential, may be a step (and cost) you want to skip.
Primer actually serves another purpose. Applying a coloured (ie: not white) primer to your parts will highlight issues. Problems such as flash, scratches and mould lines will become very obvious. This can be extremely handy when you are puttying your model, as the primer will show how well you have sanded the putty.
Thinning. Some paints are made thin enough to use in an airbrush, others are not. If your paint is too thick, you will need to thin it either for airbrushing, or maybe even just for general painting. The type of thinner you use depends on the type of paint you use.
Acrylic – can be thinned with brand-name thinner, water, methylated spirits, general purpose (GP) thinner, Isopropyl Alcohol (IPA) or even Windex. Some paints react better to different thinners. It’s worth trialling different options, since thinners like water and methylated spirits are cheap, while “real” thinners are very expensive.
Enamel – can be thinned with white spirit (aka mineral turpentine, aka mineral spirit) or brand-name thinner. Both of these thinners will give off toxic fumes and should be used in a well ventilated area.
Lacquer – can be thinned with GP thinners or sometimes with IPA. Nail polishes are a lacquer, and can be thinned and painted onto car bodies. Be aware that lacquers are “chemically hot” and can damage plastic. Make sure you parts are primed well, and apply lacquer in thin coats. Too much paint will go “furry”.