Priming & Undercoating

14 March 2018

Ok, so why bother?

In general, a well-applied undercoat helps with achieving smoother transitions, can enhance the colour and saturation of the mini and greatly influence the model.

Moreover, base coating helps the paint stick together and make painting much more easy.

In the next paragraphs, I will point out the reasons behind base coating and provide some additional tips and information regarding different colours or products you can use.

Difference between primer and undercoat:

Primer better adheres to the surface it’s on, seals porous surfaces, and allows the next coat of paint on top of it to adhere better. It’s usually used on the raw surface of whatever needs to be painted.

Undercoat can also be a primer, but usually it is a specific colour, which influences the colours on top of it (for example by increasing / decreasing saturation, or by adding additional tone beneath).

To make it simpler: primer helps paints stick, undercoat – not necessarily.

Products I tested and use in this guide:

  • GW Chaos Black Primer (best for resin miniatures)
  • GW Skull White Primer (best for plastic miniatures)
  • Valleyo Surface Grey Primer (best for metal miniatures)
  • Dremel tool (for cleaning metal minis)
  • Dishwashing liquid (to clean from fat & dirt)
  • Electric toothbrush (to make your life easier)
  • Other primers, especially the car ones – haven’t tried those, but I heard a lot of positive things about them. Even Forge World recommends them over GW (use @ your own risk!)

If you have any suggestions, or changes, feel free to add them in the comments section!

1. First, clean the model!

Aside of removing mold lines, miniatures need to be cleaned before applying basecoat.

We have three main types of materials from which miniatures are made:

  • White metal – which should be cleaned and polished
  • Plastic – which needs to be cleaned
  • Resin – which needs to be properly soaked and cleaned

Ad. A)
White metal miniatures have layer of white tint/ patina on them. This patina can make the paint not stick properly, as well cause difficulties in proper glazing, as the surface is not smooth enough.

To improve the surface, you need to clean either with a copper brush, sandpaper or a dremel tool.

Ad. B)
Afterwards, wash the parts with an old toothbrush in warm water and dishwashing liquid to remove all grime, fat (which for example comes from holding a mini in hand) and dirty things from the miniature.  This is especially important after you removed the mould lines and sandpapered some areas.

Ad. C)
Resin kits are covered in a release agent, which is used as a part of the production process. This excerpt comes directly from Forge World:

You may find that the components of your kit have a slight glossy sheen to them. This is caused by the release agent that our Production team use to remove the parts from the moulds. You will need some warm water and a mild abrasive cleaner such as washing-up liquid. Simply place the parts into the soapy water and leave them to soak for 5-10 minutes, then thoroughly scrub each part with an old (and we stress old) toothbrush. This will ensure that any traces of release agent are removed, and you can then remove the parts, rinse them thoroughly and allow them to dry.

The glossy release agent can prevent undercoat and paint from properly adhering to the model when it’s complete, and the scrubbing also gives a very slight abrasion to the surface of the model that aids the bonding of super glue.

2. Type of primer.

Lets start with one thing. Always shake the can or the paint for a few minutes.

For priming: use paint in a can or apply it from an airbrush. Don’t bother with a brush.

The idea behind the primer is to have a decent and totally smooth surface. Applying paint by a brush is counterproductive.

For specific products:

  • GW Chaos Black Primer (best for resin miniatures) – for some obscure reasons it (at least to me) works wonders with resin models – it sticks like hell and covers really well.
  • GW Skull White Primer (best for plastic miniatures) – I heard that the white primer actually dissolves a very, very thin layer of plastic. I am not sure, but for most time I use white primer on plastics models, as it covers really smoothly.
  • Valleyo Surface Grey Primer (best for metal miniatures)  – it takes couple hours  to completely dry, usually it is worth to let it dry for the night. What makes it really cool, is the smoothness of the surface. Great for metal miniatures.

From Forge World official document:

We recommend priming your model with a fine matt car body primer, such as can be found in most hardware stores. Some model primers don’t have the required solvent strength to adhere to resin properly on their own, and of course if the primer comes away then anything you have painted over it comes away too, which would be a bad thing. This pre-undercoat gives a consistency and uniformity to the surface, and can be seen in many of the photographs on the Forge World site that show plain grey models

3. Don’t overdo with the paint thickness

It is worth to remember that applying too much paint can cover some details of the mini.

4. How colors can improve your work – undercoating

Here starts the fun part : )

How the color / saturation changes depending on the color of the primer used?

As you can see, the primer has a huge influence on the saturation and intensity of the color.  Although you can increase the intensity of the color, by applying more and more layers of paint, it takes time and not all colors can be difficult to save this way (like yellow & red)

If you wish to paint a vibrant and intense colour, use white.

So, why bother with black?

Sometimes, when you want to achieve a dull and darker effect, it is better to use a black primer. Moreover in case of resin miniatures it is better to use chaos black.

Also, there is one more color technique that can help you to preshade the miniature. Spray the mini with black primer and then apply white undercoat (preferably from an airbrush – paint works better here then a primer the mini below was painted from a can, looks much better than the one I painted from airbrush…) from above.

The idea behind this, is to have some pre-shading done during undercoating. This allows us to plan better areas you want to the highlight as well as help to separate highlights and shades, by increasing the saturation of highlighted areas, and decreasing that of shades.

Want to have a more consistent colour scheme?

Apply a specific colour to your miniature?

This greatly helps in tying the miniature together as every colour has some influence from the underneath under-coat. For example, when painting Nurgle miniatures using a brown undercoat can great help achieve a nice, sick colour composition : )

Sproket used this kind of approach in the past, for his Nurgle miniatures.

5. Some additional tips, when spraying:

  • Shake it!
  • Don’t spray in a room (fumes are bad, ok?).
  • If it there is a lot of moisture outside, don’t spray there either (tiny droplets of water can get trapped under the paint, which will ruin the basecoat)
  • Don’t spray, when it is below 18C degrees (the paint will not stick properly)  As pointed by one of the readers – you can still use the paint below 15C, altough best results are around room temperature.
  • Spray firstly on a part, you will not be working on – this way you can make sure you have shaken enough and avoid the sparkle effect. It will also tell you if you have a bad spray can, or the nozzle has become clogged.
  • Don’t press the button for a long time – short controlled bursts
  • Not to close, not too far – I like 20-30 cm