How to Make Homemade Airbrush Thinner: The 70% Alcohol “Hack”
If you’ve been building Gunpla for more than a week, you know the “hobby tax” is real. A small bottle of Tamiya X-20A or Mr. Hobby Thinner can cost $10 or more. When you’re painting large Master Grades or multiple kits, that cost adds up fast.
In my recent DK Hobby video, I went on a mission to create a high-quality DIY airbrush thinner using items you can find at any local drug store. Most online recipes demand 99% Isopropyl Alcohol, but I couldn’t find any during my build.
Here is how I adjusted the recipe using 70% IPA to get a perfect, professional finish.
The DK Hobby “1:1 Recipe”
Because 70% alcohol already contains 30% water, we don’t need to dilute it as heavily as the 99% versions you see on forums.
For a 120ml bottle, use the following:
- 60ml 70% Isopropyl Alcohol (IPA): The base solvent.
- 60ml Distilled Water: To stabilize the mix.
- 2ml Airbrush Flow Improver: This is the “secret sauce” that prevents “dry tip” on your needle.
- 2ml Fluid Retarder: This slows the drying time so the paint has time to self-level on the plastic.
Step-by-Step Instructions
- Safety First: Work in a ventilated area. Even though this is DIY, you’re still working with alcohol.
- The Mix: Pour your Alcohol and Distilled Water into a clean squeeze bottle.
- The Additives: Add exactly 2ml of Flow Improver and 2ml of Fluid Retarder. Shake well until the mixture is clear.
- The Test: Always test on a plastic spoon or a piece of runner. If the paint “spiders,” you need more water; if it “beads,” you need more alcohol.
Shop the Ingredients (Save 70% vs. Hobby Brands)
To make this exact recipe, these are the items I recommend. Using these links helps support the channel and blog at no extra cost to you!
| Ingredient | Recommendation | Purpose |
| Solvent | 70% Isopropyl Alcohol | Breaks down the paint binder. |
| Base | Distilled Water | Prevents mineral buildup in your airbrush. |
| Flow | Vallejo Airbrush Flow Improver | Keeps the needle tip clean during long sessions. |
| Leveling | Vallejo Paint Retarder | Gives you that smooth, “factory” finish. |
Why This Works (Skill Arbitrage)
By using 70% IPA at a 1:1 ratio, you are creating a balanced solvent that mimics premium brands like Tamiya X-20A.
Total Cost Comparison:
- Hobby Brand: ~$18.00 per 500ml.
- DK Hobby DIY: ~$3.50 per 500ml.
That’s more money you can put toward your next MG or PG kit!
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