Getting your paint consistency right is one of the most important skills in airbrushing. Too thick and your airbrush will clog and splatter. Too thin and you'll lose coverage and colour. This guide walks you through exactly how to thin Tamiya acrylic paints for airbrushing so you get smooth, even results every time.

What You'll Need

• Tamiya acrylic paint (X or XF series)
• Tamiya X-20A Acrylic Thinner — the recommended thinner for Tamiya acrylics
• A mixing palette or small cup
• A pipette or dropper — for accurate measuring
• Spare sprue or test card — always test before painting your kit

Why Use X-20A and Not Water?

While Tamiya acrylics are water-based, plain water isn't the best thinner for airbrushing. Water can cause the paint to bead on smooth plastic, reduce adhesion, and affect the paint's flow through the airbrush. Tamiya's own X-20A Acrylic Thinner is specifically formulated to work with their paints — it improves flow, retards drying slightly (reducing tip dry), and maintains adhesion. It's an essential part of your airbrushing kit.

The Right Consistency

The most common description you'll hear is "skim milk consistency" — thin enough to flow freely but still opaque enough to provide coverage. Here's how to get there:

• Start with a 1:1 ratio of paint to X-20A thinner as a baseline
• Stir thoroughly and test on a spare piece of sprue
• If the paint spatters or feels thick, add a little more thinner
• If it's too watery with poor coverage, add a touch more paint
• Aim for a ratio somewhere between 1:1 and 1:2 (paint to thinner) depending on your airbrush and air pressure

Every airbrush is slightly different, so dialling in your ratio takes a little experimentation. Keep notes on what works for your setup.

Step-by-Step: Thinning Tamiya Acrylics for Airbrushing

Step 1 — Shake the Paint Pot Well

Tamiya acrylics settle over time. Shake the pot vigorously for 30–60 seconds before opening, or stir thoroughly with a toothpick or mixing stick.

Step 2 — Pour Paint into Your Palette or Cup

Use a pipette to transfer a small amount of paint to your mixing palette or airbrush cup. Start small — you can always mix more. Avoid painting directly from the pot as this introduces contamination.

Step 3 — Add X-20A Thinner

Add X-20A thinner drop by drop, stirring as you go. Start at a 1:1 ratio and adjust from there. The paint should flow off your mixing stick in a thin, even stream — not in thick globs.

Step 4 — Test on Sprue First

Always test your thinned paint on a spare piece of sprue or a test card before touching your kit. Look for smooth, even coverage with no spattering or pooling. Adjust your ratio or air pressure as needed.

Step 5 — Airbrush in Thin Coats

Apply multiple thin coats rather than one heavy coat. Let each coat flash off (dry to the touch) before applying the next — usually 5–10 minutes with Tamiya acrylics. This builds up smooth, even colour without obscuring detail.

Troubleshooting Common Problems

Paint is spattering or spidering

Your paint is likely too thick. Add more X-20A thinner and test again. Also check your air pressure — low pressure with thick paint is a common cause of spattering.

Paint is tip drying (drying at the airbrush nozzle)

This is common with acrylics in warm or dry conditions. Add a touch more X-20A (it has a slight retarder effect) and keep your sessions shorter. Clean the needle tip regularly during painting.

Poor coverage or colour looks washed out

Your mix may be too thin. Add a little more paint and test again. Also ensure you've primed your surface first — paint over bare plastic often looks patchy regardless of consistency.

Paint is beading on the surface

This usually means the surface has oils or release agents on it. Clean your kit with warm soapy water, rinse well, and let it dry completely before priming and painting.

Recommended Air Pressure for Tamiya Acrylics

A good starting point for airbrushing Tamiya acrylics is 15–20 PSI. Fine detail work can go lower (10–15 PSI) while base coating can go slightly higher. Adjust based on your results — every airbrush and compressor combination is different.

Frequently Asked Questions

Can I use isopropyl alcohol to thin Tamiya acrylics?

Some modellers do use isopropyl alcohol (IPA) as a thinner, but results can be inconsistent. IPA can cause Tamiya acrylics to dry too fast, leading to tip dry and grainy finishes. X-20A is the safer, more reliable choice.

How do I clean my airbrush after using Tamiya acrylics?

Flush your airbrush with X-20A thinner or Tamiya Airbrush Cleaner immediately after use. Run cleaner through until it comes out clear, then do a final flush with clean water. Don't let Tamiya acrylics dry in your airbrush — they're much harder to remove once cured.

Do I need a primer before airbrushing Tamiya acrylics?

Yes, priming is strongly recommended. Tamiya Surface Primer gives your paint something to grip and reveals any surface imperfections before you commit to painting. It makes a significant difference to the smoothness and durability of your final paint job.

Shop Tamiya Paints and Airbrushing Supplies at Aussie Hobbies

We stock Tamiya acrylic paints, X-20A thinner, surface primers, airbrushes, and compressors at Aussie Hobbies — everything you need to get airbrushing. Fast shipping across Australia.