Tamiya X-21 Flat Base 10 ml – matting additive for Tamiya paints and varnishes

Tamiya X-21 is an additive designed to reduce the gloss of Tamiya paints and clear coats. Mixed with X-22 Clear it lets you create your own satin or matt clear; added to X/XF colours it allows you to fine-tune the final sheen without significantly shifting the tone.

What it does and how to use it

• Flattens clear coats: mix with X-22 Clear to obtain a satin or matt clear finish.
• Adjusts the finish of colours: add small amounts to X/XF paints to knock back the shine.
• Important: do not apply X-21 on its own; used neat, it will leave a white, chalky haze.

Suggested ratios

• Soft satin: 1 part X-21 : 6–8 parts X-22 (≈10–15%).
• Pronounced satin: 1 : 3–4 (≈20–30%).
• Matt: 1 : 1–2 (≈40–50%). Adjust until you achieve the desired matt level without whitening the surface.

If you prefer a ready-made matt clear, use XF-86 Flat Clear (a matt varnish ready to apply).

Airbrush and brush

First prepare the mix (e.g. X-22 + X-21) and then thin with X-20A to a light milk consistency. As a starting point for airbrushing, use 1:1 with X-20A, 0.3 mm nozzle at 12–18 PSI, in light passes. For brush painting, work in thin layers and let each coat dry before applying the next.

Compatibility and cleaning

• Compatible with: Tamiya X/XF acrylic paints and Tamiya acrylic clear coats.
• Not suitable for: enamels or lacquers. For enamels, use their specific thinner (X-20 Enamel Thinner).
• Cleaning: flush the airbrush with X-20A and, if needed, an airbrush cleaner from our airbrush section.

Practical tips

• Test first: run tests on a spare piece to avoid over-matting the finish.
• Build up gradually: add X-21 little by little until you reach the satin or matt level you want.
• Thin coats: several light glazes are better than one wet coat that might cause whitening.
• Protection: work in a well-ventilated area and use appropriate protective gear.

Resources and documentation

Find more information from the manufacturer at tamiya.com. Complete your workbench with Tamiya paints, varnishes, primers and brushes.

Purchase and service

At Craftyminis, orders ship within 24/48h and shipping is free from €60. Not sure about the right X-21 ratio? Send us a message and we’ll help you fine-tune your mix and technique.