The idea for this post actually came to me as an accident while airbrushing some MDF terrain (which will go online in the near future).
Something one reads a lot from newcomers to the hobby is why to use primers and which colour to use.
The former question usually is simple to answer. The primer improves the adhesion of the paint to the model.
But which colour to use?
Well there are lots of colors these days. They come in virtually all colours. Usually these are the base colours of (historic and fictional) uniforms or vehicles. Their use is obvious… prime your model in this colour and you can skip the basic colour of the uniform or vehicles. So let us ignore all these new colours and concentrate on the classics… black and white (which also includes off-white / light grey).
Well for some the choice between the two depends on their style of painting. Some like to paint using a technique that is called “black-lining”. Essentially this technique means that each colour and / or piece of equipment is edged in black to improve the contrast between the elements of a model. Many people who paint this way love black primer. This way they just need to block in the colors and leave the edges alone. That way they do not need to paint the edges in black.
I personally do not like that painting technique and if you are the same (or prefer to paint those black lines by hand none the less) you will be free to choose. In my opinion your choice will be dictated by the colour your finished minis will have. A light coloured primer will lead to the colours that are applied on top to be more vibrant and bright. A dark primer will lead to the colours being more subdued and sinister. All in all I prefer my minis to look vibrant. Therefore I prime 90% of my minis in (off-)white. With some colours like yellow this is virtually essential to make sure they do not look dirty. In other cases it just makes the colours pop and look alive, even if they themselves are dark.
Black primer is something I only use for minis that will be predominantly black (or very dark blue or brown all over) anyway or those minis that I want to look sinister (minis where even the bright colours are meant to look bleak). In the first case it simply safes one a lot of work, in the second case, it makes the brain perceive the colours differently.
But does it really make such a difference? Is it just imagination?
Well the other day I was airbrushing some MDF terrain. amongst the pieces were two (actually more, but these were the ones I photographed) that will represent wood when done. Both had been primed*. One I had primed in off-white, since it will be part of buildings that are meant to re-present light coloured plaster. The other was primed black, since it will be part of a Bailey Bridge. (I do not want to paint the underside of the planks and neither do I want a light colour reflecting off the surface of my river. Out of pure laziness I primed both top and bottom the same.) I did spray two light coats of Vallejos Model Air “Burnt Umber” over them. Two light coats, since I wanted a shaded finish, that would make it easier to make it look like wood later on. Burnt Umber is a very dark brown, almost like chocolate with a high cocoa percentage. So what did they both look like?
As you see, two light coats over the off-white primer gave me a result, that is slightly lighter than the brown itself. Two similar coats over the black gave me a result, where you will hardly notice the brown, if at all.
By the way, this also shows how one can use these primers to ones advantage while painting. If you have a paint with a low opacity, you can use a number of coats to change your colours and create shading on your minis. If you apply a number of coats over a dark colour your colour will become lighter with every coat (more so the lighter or brighter your colour). If you apply your colour over a light colour, it will become darker with ever coat.
Hope this gives some of you some insight.
[* It is always advisable to prime MDF before pairing it. MDF is essentially sawdust pressed into shape with glue. As such it will always “suck up” lots of paint in its natural state. Priming them means that a) they suck up your cheap primer instead of your expensive paints and b) you need less coats making your work faster and easier.]