Whole books can be written about painting scale models, and I’m not going to try to replace them with a page, or even a couple of pages, on the topic. This page is to describe how I paint models (primarily structures).
Note: this isn’t really about painting but I’ll mention it here: when gluing kits or subassemblies together, don’t use super-glue on structures that have transparent parts (like windows). Even well after the glue dries there are still vapors coming from it that can “fog” clear parts.
Cleaning and Preparation
A model in kit form can have parts painted, either by hand or by spray, before assembly. Although if this is done, paint will need to be sanded or filed off plastic parts to be glued, as the glues used typically require a direct plastic to plastic bond. Snap-together structures can be unsnapped into subassemblies or parts for painting in a similar manner. Either way, some basic preparation is needed.
Note: even if you built the structure yourself out of several bags of Evergreen styrene, clean before painting. You’ll have left glue, dirt and hand oils (and likely some plastic dust) on the model, and you’ll want that off before locking it in place forever with a coat of paint.
Before painting a pre-assembled and pre-painted kit, it needs to be taken apart. Kato structures usually just have tabs with hooks on the end, that can be pried loose carefully (sometimes a flat jeweler’s screwdriver will be useful). Tomytec kits (and others) are more often glued, but levering a wide, flat jeweler’s screwdriver between parts and gradually working them apart can often separate them cleanly (the joint will need to be filed and/or sanded before re-gluing them). Some models (Kato in particular) use hidden screws to hold them together; be very careful not to strip these or damage the head by using the wrong size screwdriver (I have at least one structure I can’t take apart because a screw was damaged).
On Kato structures, often the windows are held in place both by being formed to fit into the window openings (so they have to be pushed in from the outside using finger tips to release them) and by interlocking with other windows. There may be an order needed to remove them easily (e.g., remove the side windows first, and then front-back ones). In some cases there are tabs on the inside, so you need to press in and simultaneously slide to one side (usually the “down” direction with Kato).
It’s particularly important to be careful when removing windows. The plastic used for these is more brittle than that used for the structures typically, and more prone to crack.
A plastic model will come from the factory with dust and dirt on it from handling, possibly oils from the hands of the people who put it together or packed it, and often with “mold release” chemicals on it from the manufacturing process if it wasn’t pre-painted. Resin kits will usually have mold release as well. All of these will interfere with paint adhering to the model. So the first order of business is to clean the parts to be painted.
Note: it should be obvious, but don’t wash wooden kits or parts!
Wear rubber gloves while cleaning, so your own skin oils don’t end up on the model. If you use nitrile gloves, make sure they aren’t powder-coated so you don’t leave powder on the models (or wash the gloves with soap and water after you put them on to remove any powder).
0. Remove any old glue, model sprues, etc. before cleaning. You can paint parts on the sprue, and cut them off later, as long as the sprue connects somewhere that won’t be visible on the finished model, or you’re going to hand-paint that spot later.
1. Separate the parts into individual parts or at least sprues or subassemblies that will be the same color.
2. Wash these in lukewarm water (NOT hot; you don’t want it to deform, and styrene starts to bend at fairly low temperatures). Use a few drops of dish detergent in a kitchen sink or similar-sized basin. This will help remove dirt particles. Scrub parts with an old toothbrush with frayed bristles if you can, to loosen any material on the surface or in joints or cracks. Agitate the parts (move them back and forth rapidly in the water by hand) to shake any loosened dirt remaining off as the last step before rinsing.
3. Rinse well with clean running water and shake to remove as much surface water as you can. Make sure there’s no soap film or suds left on the surface or in cracks. Working near a window with sunlight, or a bright task light, can make examining the surface easier.
4. If possible, use “canned air” or air from an airbrush compressor to blow any remaining water off the surface; this prevents any dirt or other contaminants left in the water from being redeposited. Otherwise, just shake the part very well until it looks dry.
5. Set aside (on a clean towel or similar) to fully dry. Don’t use a towel treated with fabric softeners that may leave chemicals behind (paper towels work better, I think). I usually leave things to dry overnight, but in dry winter air a few hours is probably sufficient. But you don’t want any moisture left on the part when you paint it.
Priming and Base-Coating
Most models don’t require priming, however metal parts (such as castings) may benefit from a primer designed for metal. In addition, putting down a uniform base color (such as white) is very helpful if you are pairing a pre-painted structure that has multiple colors on it, to prevent any of that from showing through.
Some pre-assembled structures are made using a slick “ABS” type of plastic. These will benefit from having a uniform coat of some kind to help other paint adhere to it.
If the item being painted is part of a structure that will be lit, and you don’t want the light showing through, you will need a good base coat of an opaque color, like flat black, to prevent this.
A base coat should typically be white, as this will not alter colors painted over it by “showing through” them.
My standard technique is that anything gets two coats of flat white as a uniform base for other colors. In addition if the object will be lit, I first apply two coats of flat black before adding the two coats of white. Interior walls and roofs may be left white, to serve as a reflector for lighting, or may have other colors applied over this. Exteriors will always have some other color applied over the white.
The reason I use two coats is that with spray paint, it’s easy to either miss one spot or to leave an area more lightly-coated without realizing it. Two coats ensures that you can fix any spots you didn’t get the first time without being tempted to put down a very thick first coat that could hide details, and will provide a more uniformly opaque coat.
It’s important that the base coat not hide details. This is where an airbrush is very handy, but if you brush-paint you can still apply the base coat from a spray can.
However, many spray-can white paints don’t provide very good coverage. My current (pre-airbrush) method is to use Tamiya white primer as the base coat. I use Model-Master flat black for a light-blocking coat. These seem to work fine together.
If there are parts you don’t want painted (e.g., hidden tabs you will want to glue to something later) these can be coated with “frisket” film (self-adhesive paper for masking during airbrushing). Using masking tape generally won’t work very well, as it’s too coarse to seal well to plastic (I have however used it successfully where keeping “most” of the paint off is all that’s required).
Once you finish your base coats (light block and white base), which should all be done quickly after each coat visibly dries, leave the model to sit for at least 24 hours for the paint to “cure” before doing any masking or color painting.
Here’s a somewhat odd base coat: windows and other clear parts can be treated in a bath of Future Floor Polish to protect them against dirt, finger prints, and fogging by super-glue fumes. See the section on protective coatings below for more on this.
Acrylic, Enamel and Lacquer Paints
There are three kinds of paint (and many “hybrid” forms that are somewhere in between). Most “model paint” is enamel, some newer paints are acrylic (usually these will be water or alcohol-based and can be cleaned up after with soap and water, rather than using special thinners for cleanup). Lacquer paint isn’t much used any more (the pre-2000 formula for Floquil paint was a lacquer, but this was replaced with an enamel after Testors bought the company). However, some coatings (like Dullcote) are still lacquers.
As a general rule: don’t mix different kinds of paint on the same model. That’s not an absolute, but life will be simpler if you pick one brand and stick with it for a given model.
A rule of thumb is that lacquer paint can be coated by anything, enamel paint can be coated by enamel or acrylic, and acrylic paint should only be coated with acrylic. This isn’t true in all cases, since paint formulas vary so much. In particular, Tamiya acrylic can reportedly be overcoated with enamel paints. If you’re going to mix paint types, it’s probably a good idea to experiment on some scrap plastic first.
This is supposedly related to the thinner used: stronger thinners (in enamel, for example) can affect the finish of paints based on weaker ones (like acrylics).
When brush painting, paints are usually applied straight from the bottle. However they can be thinned, which will make them more runny. This helps when painting things with lots of fine detail, since the paint will flow into cracks better. But it can also make the paint “run” in ways not desired if not used carefully.
When airbrushing, paint typically needs to be thinned “to the consistency of skim milk” using a specialty airbrush thinner (some acrylics can be thinned with alcohol, but don’t use “rubbing alcohol that’s only 70% or 80% alcohol). While some people have thinned some acrylics with water for airbrushing, it’s generally not a good idea as water doesn’t do a great job of evenly diluting the pigment.
Ink and Other Washes
A “wash” is any pigment diluted to be very thin, and then applied to a model (usually by brush but sometimes by dipping) so that the pigment will stick to details or make thin coats (like rust dripping from a rusty rivet, for example). The usual use for washes is in weathering, but they can also be used where a light pigment needs to be applied over some other color (e.g., rust powder from wheels and rails coating gray ballast on tracks).
From what I’ve read, it’s better to use acrylic ink than india ink for this purpose.
When water is used, something must be added to reduce surface tension. Ordinary dish detergent can be used, but liquid spot remover for dishwashers is said to be better.
This term, which comes from the military miniatures hobby, refers to a detail-enhancing color wash (usually black) created using an acrylic thinner, and in particular to Future Floor Polish (see Coatings section at bottom of page) used as such a thinner. Some people prefer to use “flow improvers” (essentially thinners designed for brush painting acrylic paint) instead. There are probably as many formulas for this as there are modelers. While this originated among figure modelers, it could be helpful on models with fine detail.
The basic idea is for the tint to end up in deep crevices or against sharp edges, forming “shadows” to help bring out the dimensionality of the structure. Future works as a thinner with acrylics to make them more fluid.
Formulas often use one part Future to several (3-4) parts water, with a small amount of paint or ink (could be as much as 1 part, but usually less), plus a surface-tension reducer.
A dark black wash formula (I haven’t used yet, but plan to) is:
4 oz (118 ml) Future acrylic polish
4 oz (118 ml) distilled or boiled water
1 teaspoon (5 ml) liquid dishwasher spot remover
50 drops (2.5 ml) opaque black acrylic ink
and shake well to make 8 oz of wash.
Use of brown ink may be better (highlights but looks more like rust/dirt than black does).
A lighter black wash (but a glossy one), for bringing out detail (from the same source) is:
120 ml Future
4.5 drops India Ink (comments suggest India ink is a bad choice, and acrylic is better)
(since no water is used, the spot remover to break the surface tension of water isn’t needed either)
Protective and Other Coatings
Flat paint is more prone to damage from handling than glossy paint. And quite often if you have glossy paint, or apply decals to flat paint, you will want some kind of sealer that makes it flat. I don’t have a lot of experience with this myself, but I’m going to include some general notes based on online reading for reference here.
Since decals are glossy, it’s typical to apply a gloss coating before applying decals, then apply a dull coating after. This prevents the transparent material around the decal from being visible, and keeps the model as a whole “flat” (which is what you want for most models), as well as creating a protective seal over the decal.
A flat coat (or other coating) can also be applied over weathering powders or inks to seal them in place.
In all cases, paint should be allowed to dry for at least 24 hours before applying any coating.
Testors Dullcote and Glosscote
These are, as the names imply, dull and glossy overcoats. They are (per the manufacturer) lacquer-based and come in both spray-can and bottled (for airbrushing) form. These need to be applied in thin (“mist”) coats, with multiple coats applied until the desired effect is achieved.
Although these are lacquer-based coatings, they can be used safely over their own brands of enamel or acrylic paint according to the manufacturer. And online reports suggest they can be used over Tamiya acrylics also.
Note however that a thick coat of dullcote will tend to be glossy, and using a spray-can rather than an airbrush to apply it can run into this problem when applying over some acrylics, or at least so say some people online. Others don’t have that problem. If you’ve applied too much dullcote and it turns glossy, apply a gloss coating, let dry, and then apply a thin coat of dullcote.
I’ve read of some people having problems with dullcote yellowing over time, but others don’t have this problem. It could be due to exposure to sunlight (which is bad for model paints in general and will turn white paint yellow in particular) or some interaction with the specific paint used on the model.
Future Floor Polish
It’s a Floor Wax, it’s a Desert Topping! Well, okay, apologies to Saturday Night Live (and if you don’t remember that skit, you’re too young). But it’s a floor wax that’s used as a coating or paint thinner with acrylic paints. Which is just plain weird.
Future Floor Finish (a product and trademark of the S. C. Johnson Co.) is widely used by modelers as a protective coating. It provides a clear gloss coating by default. It won’t look glossy at first, but will dry glossy. It can be mixed with other things to provide a non-glossy coating. True Future is a clear liquid. There’s a variant formula used in Australia that’s a milky white liquid which works similarly, but has been reported to have problems over Tamiya acrylic paint.
Future is now marketed (in the U.S.) as “Pledge Floor Care” but has the same formula. It is sold in other countries under different names. There are apparently some other formulations as well, so if you aren’t sure what you’ve got is “Future”, it’s a good idea to test first. Future, by any name, is a water-soluble acrylic coating, and thus a much healthier substance to work with than lacquer-based coatings.
It can be applied via airbrush without thinning, or thinned with either denatured alcohol or Isopropyl alcohol. When airbrushing, two separate coats are recommended. The substance is relatively thick, so weathering with washes to bring out highlights is best done before applying it, not after.
It can also be used as a bath for clear parts like windows, to protect them from super-glue fumes and provide a glossy shine (be sure to wash the parts first as described above). You can paint over this (with acrylics anyway; I don’t think I’d use enamels) to do window frames or other details. One technique I’ve seen described is to dip using tweezers, hold until most liquid drains back into the bath, and then set down on paper towels to finish drying. Be careful not to dip quickly, as this can form bubbles.
And it can be used as a thinner for acrylic paints, either for brush painting or in washes (see Magic Wash description above).
It is possible to apply by brushing it on with a clean brush, working slowly to avoid forming bubbles.
Ammonia dissolves Future, and Windex (which contains ammonia) is a good airbrush-cleaner for use after brushing with it.
It can also be made less glossy: one formula for this I’ve seen (apparently from a Fine Scale Modeler article) is:
It can be mixed with a flat base such as Tamyia's X-21 to create semi gloss and flat coats.
1) For dead flat use 3 parts Future to 1 part flat base.
2) For flat use 10 parts Future to 1 part flat base.
3) For semigloss use 15 parts Future to 1 part flat base.
I have read multiple reports of it having problems on automobile models. This may be because auto models are often painted with lacquer paints, but I don’t know for certain.