I get asked about thinning paints a lot. Things like:
- Should I thin paint?
- If so, then how much?
- What should I use to thin my paint?
- How do I get my paint to work in an airbrush?
I can easily give a straight answer to the first question. Yes, you should always thin your paint before you use it. If you are using a brush and you do not thin the paint then you risk loosing a lot of detail on your model from built up paint and you will be unable to get a nice smooth coat. If you are using an airbrush and don’t thin you paint, it will probably not even spray.
Unfortunately, the remaining questions are not as straight forward to answer, so I have to say, “It depends,” and dive into an explanation. I will try to deal with some of these issues here. For this post, I am going to focus on brush painting. I will do a similar post discussing airbrushing later.
How much should I thin my paint?
When your mini is dry you want it to look like the surface of the miniature is the color of the paint, not like there is a layer of color on top of the miniature. This will preserve all of the details of the miniature and give the most realistic appearance. Additionally, you do not want any brush strokes in you finished work. To get these effects, you will need your paint to be quite thin and you will need to apply several coats to get an even color.
So the question becomes, how much thinner do you add? The answer depends on the specific paint you are using and the effect you are trying to accomplish. Typically, when base coating and layering you want the paint this enough to cover the surface and to flow flat with the surface of the miniature. If you get puddling of the paint or you can see brush strokes, then it is too thick. If your paint does not stick to the surface and tends to run, then it is too thin. A good starting point for Games Workshop, Vallejo Model Color and Vallejo Game Color is to start with a 2 : 1 ratio of paint to thinner and add thinner until the paint goes on smooth and flat. If you are glazing or highlighting you will want an even thinner mix.
At first, it may seem difficult to paint with the thinned paint, just stick with it and remember it will take a few more coats to get good coverage, but your miniature will look a lot better when you are done. Once you get used to working with thinned paint you will find it impossible to work with paint out of the bottle.
What should I use to thin my paint?
This answer depends on the type paint you are using.
- Acrylics – I generally tell beginners to use distilled water if you happen to have some or tap water if you don’t. For more advanced painters, I suggest you try what I use, distilled water and Liqutex Flow Aid at a 10:1 ratio of distilled water to Flow Aid. The Flow Aid reduces the surface tension of the paint a little and allows it to better flow onto the surface of the miniature. I keep my thinner in a dropper bottle to make it easy to add to my paint and get a consistent result. Some people will tell you to only use the manufacturers acrylic thinner. They will explain that it will keep the pigment more evenly distributed longer and will have better adhesion. This may be true, but for painting miniatures, I have never had a problem with distilled water and Flow Aid. So, I stick with what I know and save money in the mean time. Another option favored by a lot of modelers is to use Windex. This is particularly popular when thinning for use in an airbrush. I have tried this and it works well. The Windex gives about the same effect as the Flow Aid / water mixture, but I prefer the smell of water to Windex
- Oils – Currently, the only oils I use are the Winsor – Newton Artisan water mixable oils. They have the benefit of the long drying time of traditional oils and the benefit of being thinned and cleaned with water. If you are going to use traditional oils, then I recommend a odorless thinner like Maimeri Odorless Thinner. It does the job and does not stink the place up as bad as other thinners.
- Enamels – I typically recommend using of the same brand of thinner when using enamels, i.e. if you are using Testors enamel paint then stick with the Testors thinner. I know a lot of modelers that use lighter fluid to thin their enamels with no problem, so you are probably OK. Be careful of lacquer thinner. It can damage plastic, so you should avoid it.
I hope this answers a few questions about thinning paints for modeling. If you have any questions, just leave them in the comments.