How to Paint Gunpla with Mr. Color C78 Gloss Metallic Black

By Newtype: Gundam Model Kits / Gunpla / Paint / Tools | Published: 2026-10-28

Category: How-to Guides

Learn to airbrush Mr. Color C78 Gloss Metallic Black for a smooth, mirror-like finish on your Gunpla. Step-by-step tips for thinning, layering, and troubleshooting.

Quick Answer

For a smooth, reflective black on your Gunpla, airbrush Mr. Color C78 Gloss Metallic Black in thin, even coats over a gloss black primer, then protect it with a clear gloss topcoat.

Why Gloss Metallic Black Differs from Flat Black

Mr. Color C78 is a gloss metallic paint, meaning it dries to a shiny, reflective surface that mimics polished metal. Unlike flat black, it shows every surface imperfection, so surface prep is critical. The metallic flakes also need a smooth base to align properly; a rough primer will scatter light and dull the effect.

Airbrushing vs. Hand Brushing Trade-offs

Airbrushing is the recommended method for C78 because it lays down an even, thin film that lets the metallic particles settle uniformly. Hand brushing can work on small parts but often leaves brush strokes and uneven gloss. If you must hand brush, use multiple very thin coats and avoid going back over a semi-dry area.

Step-by-Step Painting Process

Prepare the Surface: Wash the parts in warm soapy water to remove mold release, then sand with fine grit (800-1000) to eliminate seam lines and imperfections. Wipe with a tack cloth. Checkpoint: Run a finger over the surface—it should feel perfectly smooth. Any roughness will show through the gloss.
Apply a Gloss Black Primer: Spray a thin coat of gloss black primer (like Mr. Surfacer 1500 Black) and let it dry completely. This provides a slick base that helps the metallic flakes lie flat. Checkpoint: The primer should be glossy and free of orange peel. If not, lightly sand and reapply.
Thin Mr. Color C78 Properly: Mix Mr. Color C78 with Mr. Color Thinner at a ratio of 1:1 to 1:1.5 (paint to thinner). Stir thoroughly—do not shake—to avoid bubbles. Checkpoint: The mixture should have the consistency of skim milk. If it's too thick, it will clog the airbrush; too thin, it will run.
Airbrush in Thin, Even Coats: Set your airbrush to about 15-20 psi. Spray from a distance of 10-15 cm, applying light, overlapping passes. Build up color gradually with 2-3 thin coats, allowing each to dry for 10-15 minutes. Checkpoint: Aim for a uniform sheen without any wet pooling. If you see runs, you're spraying too much or too close.
Let It Cure and Protect: Allow the paint to cure fully for at least 24 hours before handling. Then apply a clear gloss topcoat (like Mr. Color GX100) to protect the metallic finish and enhance the gloss. Checkpoint: Test the topcoat on a spare part first to ensure compatibility and avoid a frosted look.

Product Facts

Mr. Color C78 Gloss Metallic Black 10ml: Mr. Color C78 is part of the Mr. Color line, a paint long regarded highly by modelers worldwide for delivering an excellent finish. This reputation means you can trust the paint to level well and produce a consistent metallic sheen when applied correctly.
Mr. Color C78 Gloss Metallic Black 10ml