Airbrush Flow Improver: When and How Much to Add
By Quality Tools & Supplies for Hobbys, DIY & Crafts - Micro-Mark Tools | Published: 2026-10-16
Category: How-to Guides
Learn when to add flow improver, how much to mix, and how it differs from thinner. Includes a simple ratio guide and a tip-dry fix for acrylic airbrush paint.
Quick answer
Add flow improver to acrylic paint when it sprays too dry, dries on the needle tip, or leaves a grainy finish. Start with 1 drop per 10 drops of paint, mix well, and test on scrap. Increase gradually—up to 1 drop per 4 drops for tip-dry issues—but stop before the paint becomes runny or loses coverage. Flow improver is not a thinner; use thinner when you need to reduce viscosity without extending drying time.
Flow Improver vs Thinner: What’s the Difference?
Flow improver and thinner both change how acrylic paint sprays, but they do different jobs. Thinner reduces viscosity so paint atomizes at lower pressure, but it also speeds drying and can weaken adhesion if overused. Flow improver slows the drying time of the paint film, allowing it to level out and preventing it from drying on the needle tip. It also improves how the paint flows off the brush, reducing spatter and improving self-leveling.
Use thinner when paint is too thick to spray even at higher pressure. Use flow improver when paint sprays but dries too fast, causing tip dry, or when the finish looks rough or orange-peeled. Many airbrush artists use both: a small amount of thinner to reach spraying consistency, then a drop of flow improver to extend open time.
When to Add Flow Improver (and When Not To)
Add flow improver when you see tip dry—paint accumulating on the needle tip and spitting. It also helps when spraying in dry or hot environments, when using fast-drying acrylics, or when you need a smoother blend on miniatures or models. If paint is already thin and watery, flow improver will make it worse; in that case, add a small amount of medium or thicker paint instead.
Do not use flow improver as a substitute for proper thinning. If paint is the consistency of heavy cream, it needs thinner first. Also avoid adding flow improver to metallic or pearl paints beyond the recommended ratio, as it can dull the metallic flake orientation.
How Much Flow Improver to Add: A Simple Ratio Guide
Start with 1 drop of flow improver per 10 drops of paint (10%). Mix thoroughly with a pipette tip or brush handle. Spray a test pattern on scrap cardboard or paper. If tip dry persists, add another drop per 10 drops (20%). For stubborn tip dry or very dry climates, go up to 1 drop per 4 drops (25%). Beyond 30%, paint may become too transparent and runny.
For airbrush-ready paints that already contain flow improver, add none or at most 1 drop per 20 drops. For thick craft acrylics, you may need to thin first, then add flow improver. Always add flow improver to the paint cup, not the airbrush body, and mix gently to avoid introducing bubbles.
How to Fix Tip Dry with Flow Improver
Tip dry happens when paint dries on the needle before it reaches the surface. To fix it, first clean the needle tip with a soft brush and acrylic cleaner. Then add flow improver to your paint mix as above. If tip dry continues, try lowering air pressure to 15–20 PSI and spraying closer to the surface. Also check that your needle and nozzle are not damaged; a bent tip can cause spatter that mimics tip dry.
For a quick field fix, keep a pipette tip dipped in flow improver and touch it to the needle tip between passes. This re-wets the dried paint without flushing the airbrush. If you use a micro pipettor for measuring additives, graduated pipette tips make it easy to add precise amounts.
Step-by-Step: Mixing Flow Improver into Acrylic Paint
- 1. Shake and prepare your paint: Shake the paint bottle thoroughly. If using thick craft acrylic, pre-thin with a few drops of thinner or water until it flows like milk. Do not add flow improver to unthinned heavy paint—it will not mix evenly. Checkpoint: Paint should drip off a mixing stick in a steady stream, not plop.
- 2. Add flow improver at 10% ratio: Use a pipette to add 1 drop of flow improver per 10 drops of paint. For a typical airbrush cup (about 10 drops), that’s 1 drop. Mix with a pipette tip or brush handle for 10–15 seconds. Common mistake: Adding flow improver directly to the airbrush cup without mixing—it won’t distribute evenly.
- 3. Spray a test pattern: Spray on scrap cardboard at your normal pressure (15–25 PSI). Look for a smooth, even coat with no spatter or tip dry. If the paint looks grainy or dries on the tip, proceed to step 4. Checkpoint: If the test pattern is runny or transparent, you’ve added too much—add a drop of unmodified paint to balance.
- 4. Increase to 20% if tip dry persists: Add 1 more drop of flow improver per 10 drops of paint (total 2 drops per 10). Mix and test again. For very dry climates or fast-drying paints, you can go up to 25% (1 drop per 4 drops). Stop at the lowest ratio that solves the problem; more flow improver means longer drying time and potentially weaker adhesion.
- 5. Clean the needle tip between color changes: Even with flow improver, paint can accumulate. Wipe the needle tip with a soft brush dipped in acrylic cleaner. This prevents dried paint from causing spatter and keeps the airbrush working consistently. Next step: If tip dry continues after 25% flow improver, check your needle and nozzle for damage or switch to a slower-drying acrylic.
Products that help with flow improver mixing and cleanup
- Pipette Tip, 1 - 200uL, 50 Pack: Graduated tips for accurate measurements; universal, airtight fit; designed for the Diamond Pro Micro Pipettor but compatible with most other brands. Precise drop-by-drop addition of flow improver prevents overthinning and makes ratio experiments repeatable.
- Micro-Mark Acrylic Paint Cleaner , 20ml: Specially formulated to clean brushes, palettes, and tools used with water-based acrylic paints; safely breaks down dried paint without harsh fumes. Keeping the airbrush needle and tip clean between color changes reduces tip dry and ensures flow improver works as intended.
- Micro-Mark Aluminum Acrylic Paint, 20ml: Bright, metallic silver tone replicates bare aluminum surfaces; smooth, reflective finish creates natural highlights and contrast; pairs well with Gunmetal, Iron, and Metallic Silver for realistic metal effects. Metallic acrylics like this benefit from flow improver to prevent tip dry, but adding too much can dull the metallic sheen, so stick to the lower end of the ratio range.
