Should I use matt, satin or gloss varnish on a model?

People treat varnish as the last step, and half of its uses are not at the end at all. Understanding it as a working surface as well as a finish is what makes decals, washes and weathering behave, and it explains why a matt model has a gloss coat buried in the middle of it.

Safety

Step by step

1. Use gloss as a working layer, not a finish.A gloss coat over the base colours gives decals a smooth surface so they do not silver, and gives a wash a non-absorbent surface so it can be removed from the flat areas. On most builds this is the first varnish that goes on and it is never the last.
2. Use matt or satin as the finishing coat.It unifies the sheen across gloss coats, decals, differently pigmented colours and weathering, so the model reads as one object rather than a collection of surfaces. This is what actually makes a mixed-media paint job look finished.
3. Default to satin rather than true matt.Dead flat matt is flatter than almost anything real, including old paint, and it can make a model look chalky and lifeless in photographs. Satin, or matt with a small amount of gloss mixed in, reads much more like a real painted surface.
4. Vary the sheen deliberately across the model.Rubber, canvas and dirt are matt; metal, glass, wet areas and leather are not. Selectively brushing gloss varnish onto specific areas after an overall matt coat is a cheap and highly effective touch of realism.
5. Shake matt varnish for far longer than you think.The flatting agent that makes it matt is a heavy solid that settles at the bottom. Under-shaken matt varnish sprays as gloss first and matt later, which is the second most common varnish complaint after frosting.
6. Never spray varnish when it is cold or humid.Matt varnish is more prone to frosting than any other coating, because the flatting agent plus condensed moisture produces a white bloom. This ruins finished models more than any other single mistake at the end of a build.
7. Build it up in thin coats.Two or three light passes rather than one wet one. A thick varnish coat pools in recesses, dulls detail, and takes a very long time to harden, during which the model collects dust and fingerprints.
8. Let it cure hard before handling or storing.Varnish stays slightly soft for days. Putting a model in a display case or handling it heavily in that window leaves permanent marks and, if two surfaces touch, they can bond together.

Tips

• Mixing your own sheen from matt and gloss varnish of the same brand gives you exactly the finish you want, and is much cheaper than buying three cans.
• For gaming miniatures that get handled, a hard gloss varnish first for protection followed by a matt coat for appearance is far more durable than matt alone, which is a soft coating.
• Test the spray on a scrap piece painted the same way before it goes on a finished model. A ruined varnish coat on a finished model is heartbreaking and largely unrecoverable.

Common mistakes

• Spraying matt varnish on a damp day — It frosts. The finished model comes out with a white chalky bloom over the paintwork, and because it is the final coat there is nothing above it to hide the damage.
• Skipping the gloss coat because the model will be matt — The gloss coat is a working surface for decals and washes, not a finish. Without it, decals silver and washes stain permanently, and both are visible under the eventual matt coat.
• One heavy varnish coat — It fills fine detail, pools in recesses and cures slowly, so the model picks up dust and fingerprints for days and the detail you painted disappears.

If it doesn't work

Questions people ask