Basic Course in the use of Acrylic Mediums for Miniatures Painting

A basic course in Acrylic Mediums

This is meant as a basic primer in the purposes and use of various Acrylic Mediums (fluids) available on the market to help improve your miniatures painting abilities.

Glazing medium

All acrylics are designed to be thinned with water and many people glaze perfectly well using only water as the thinner. At a certain point however, adding too much water dramatically thins the amount of suspension/binding medium that is an essential part of the paint at which point it loses it’s consistency and ability to stick. This is that point where so much water is in the paint that it doesn’t leave brush strokes anymore and instead it leaves a trail of beaded droplets and ‘bald spots’.

Glazing medium is a way to maintain the integrity of the paint while still thinning the pigment count; it is essentially thinned suspension medium, designed to maintain all the qualities of the paint while modifying it’s transparency.

This is where the term ‘glazing’ comes in. In essence you are dealing with a thicker wash with one critical difference; Washes are primarily designed to pool in recesses while glazing is in effect applying the paint via traditional, controlled brushwork, not just blobbing an entire area.

You build the color by layering the now semi-transparent paints over and over until you achieve a flawless blend, modifying the colour one small step at a time.  In addition to the way you apply a glaze being different, a wash tends to be a lower viscosity fluid to facilitate it easily and automatically getting into the cracks and recesses. Generally, this is done with the introduction of a flow aid as well as the glazing medium, and most flow aids make the end result slightly glossy while glazes should dry matte.

Glazing works particularly well over white, and the two together can achieve very vibrant but still entirely natural looking results.

It is not always necessary to use a glazing medium to achieve a glaze. However, use of glazing medium is a small step that can be taken to ensure that you will not over-thin and ruin your glaze.  Glazing without using a glazing medium can be a bit unforgiving until you get a feel for it.

Flow aid (dispersant medium) 

Flow aid is somewhat self explanatory. It applies to any additive that lowers the viscosity (ie: surface tension) of the paint. What does that mean? It means that the paint flows better, that it lies flatter to the surface and in many cases is generally easier to work with.

What is viscosity? The answer is rather complex actually, having to do with some pretty advanced fluid dynamics , but for simplicity, let’s just say viscosity is a question – ‘How much does this fluid stick to the side of a glass?’. Picture putting, say, honey in a cup. Swirl it around, or try to. It does not flow easily, it sticks to the sides etc etc. This is high viscosity. For low viscosity, think of something like vodka, or future floor polish. It flows like grease on ice, leaves almost no residue on the sides of the cup.

In essence, we are talking about liquid friction, a fluid’s ability to stick to itself and other things, how easily a droplet can be released from the main body.

So, basically, flow aid turns your half and half cream paint to vodka paint, or somewhere in between.

Retarding Medium (Slow dry) 

This is another fairly self-explanatory medium. Adding Retarding Medium to your paints will slow the drying time by quite a bit, giving it an oil like quality for a while (how long depends on how much retarder you add).

Why do it? If you are into wet blending using retarder is almost mandatory.

For those who don’t know, wet blending is, in the most basic of explanations, a technique involving putting two blobs of different coloured paint beside each other and then blending them into each other with the brush to achieve a smooth, even blend from one colour to the next.

Like a well applied glazing session, an acrylic retarding medium used in combination with wet blending techniques allow you to reach an essentially seamless transition between colors.


Thinners are a bit of a vague category. What a thinner is seems to differ based on what you are doing.

For an airbrush, a thinner is something like a brand thinner, isopropyl alcohol, windex or even plain old water. Thinning is almost always mandatory with an airbrush in order to get it to function properly as the tiny nozzle needs as thin and low viscosity fluid as you can get without compromising the paint in order spray properly.

With brush painting thinner almost applies to anything that could be considered a dilutant; water, flow-aid, etc. In general, you will probably end up with a flow-aid type fluid if you buy ‘model thinner’, whereas you will get a diluted alcohol type fluid if you buy airbrush thinner.

Matte, Satin and Gloss Mediums

All miniature painters are (or should be) fairly familiar with these, at least in terms of sealers for finished work. Each has some interesting applications for the actual painting process itself as well. An example being temporarily putting a gloss finish on a model in order to lower viscosity even more and make washes flow like butter in a hot pan (they will find and sink into recesses even more effectively than normal). Gloss sealer also facilitates better contact between a decal and a surface, making it flatten and adhere better than normal (aided even more by decal fluids, but that is another bag of beans).

Matte, gloss and satin mediums were not created expressly as sealers, that is a secondary function; painters sometimes employ them to modify or protect their canvases. These mediums are actually meant to be used to modify the qualities of paint colors! Most painters with a bit of experience will note that certain colors, and certain types of liquids like washes, exhibit their own finish qualities.

So, what do you do do if you want your black to come out shiny like a patent leather? What do you do if you want your black flat like soot? The simple answer is to add a drop or 2 of the appropriate medium/varnish/sealer (whatever your brand calls it) and  your color will be modified with the reflective qualities you were looking for.  Simply bear in mind the reflective qualities of the material you are trying to simulate via painting, and use the appropriate mediums to ensure your paint will work with you and not against you.

Suspension/Binder medium

This is what is at the core of all acrylic paints.  Suspension/Binder medium is the polymer resin emulsion that allows the pigments to float without pooling at the bottom and gives the paint it’s plastic like quality when it is dry. If you want to make your own paint, all you need is fine ground pigments, binder medium, flow aid and distilled water.

Not everyone will need this, but it is very cool if you are adventurous. It is also useful if you want to modify a paint you already have and thicken it.

To Recap

Glazing medium – Used to create translucent, but very controllable paint. Used to build up smooth, bright transitions, especially vibrant when used over a white basecoat. Glazing paint should behave the same as normal paint (after you of course thin the normal paint with a bit of water as usual)

Flow Aid/Dispersant medium – Generally a good idea in almost any paint style. This makes the paint flow and cover better, reduces lumpy brush strokes and makes the paint settle closer to the surface. Also an important (nearly essential) ingredient for making washes and inks.

Retarding medium – Very helpful for those who employ advanced blending as it gives you more drying time while you perfect your work. Not helpful for fine line details or edging.

Thinner – Function and use very contextual, generally will do what it sounds like it will however : thin your paint.

Matte/Satin/Gloss Medium/Sealer/Varnish – Can be used to modify the finish of dried paint, can be used to protect work after completion, can be used to enhance the effects of viscosity based capillary action, can be used to enhance contact between surfaces for things like decals and crazy glue.

Suspension/Binder medium – Used to create custom paints or modify/thicken existing paints.  Not likely of use to most.


You will find the more you learn, the more you will find that all acrylic paints are essentially usable for mini paintings, some art or craft paints being superior even! It is all simply a matter of pigment count and understanding how to modify the paint using the above mediums to a consistency you like for your miniature painting. As long as the pigments are good, you can turn any paint into miniatures paint, so experiment with anything you can get your hands on!

Don’t forget that these mediums apply to any type of acrylic painting, from miniatures to canvas and everything in between.