Airbrush Thinner Guide: Which Thinner for Which Paint, and How Much

Thinner, reducer, flow improver, retarder: what's the difference?

Product type	What it does	Example
Thinner (reducer)	Lowers viscosity so the paint atomizes	Vallejo Airbrush Thinner 71.261; Createx 4011 Reducer; Tamiya X-20A
Flow improver	Slows drying in the airbrush, which cuts tip dry	Vallejo Airbrush Flow Improver 71.262
Extender or transparent base	Makes color more transparent without thinning it	Golden Airbrush Transparent Extender; Createx 5601 Transparent Base
Mixing clear	Adds resin for adhesion and toughness, often then thinned	Createx 4030 Balancing Clear; Createx 4050 UVLS Gloss Clear

Createx's 4011 data sheet is a good illustration of why a thinner is not just water: it lowers viscosity for better atomization and flow, reduces tip dry and improves drying and curing. It contains no resin, so Createx warns against over-reducing and says to extend colors with a resin-based clear instead.

The thinners, maker by maker

Vallejo Airbrush Thinner 71.261 and Flow Improver 71.262

Vallejo's thinner page gives two limits: airbrush colors take a maximum of 25% thinner, brush-on colors a maximum of 50%. Its Model Air chart recommends 1 part thinner to 3 parts paint, mixed in the airbrush cup, with the compressor at 1 to 1.5 kg or 15 psi. Flow Improver slows drying when airbrushing; Vallejo recommends 3 drops of paint to 1 of Flow Improver at the same pressure. Both come in several sizes (the thinner in 18, 32, 60 and 200 ml).

Createx 4011 Reducer

4011 is Createx's standard thinner for all its paints and clears. The data sheet says to add it generally at 5 to 10% per volume, in 5% steps, adding more only when needed for flow and fine atomization, and up to 20% for low-pressure work with small tips (it names Iwata's 0.18 mm Micron). Let the mix stand 10 minutes or more before spraying. Createx's application guides give higher figures for mixes that include its clears: about 20% for airbrush on its own, about 30% when 4050 clear is in the mix. The data sheet says it supersedes inconsistent information, including the label. Thinned paint is best used within 48 hours, because the reducer speeds evaporation of water from the paint.

Tamiya X-20A

Tamiya's page says X-20A is for diluting or cleaning away Tamiya Color Acrylic paints. It gives no ratio. Thin in small steps and test on scrap until the spray is smooth.

Water, for Golden High Flow

Golden says High Flow Acrylics spray from the container; for small adjustments add water, but over 20% water begins to change other properties. To make High Flow more transparent, Golden recommends Airbrush Transparent Extender, which does not thin the paint.

Ratios at a glance

Paint	Thinner	Maker's ratio	Maker's pressure
Vallejo Model Air	Airbrush Thinner 71.261	3 paint : 1 thinner (max 25%)	About 15 psi
Vallejo brush colors	Airbrush Thinner 71.261	Max 50% thinner	Not given
Createx Airbrush Colors, Wicked	4011 Reducer	5 to 10% per volume (up to 20%)	60+ psi unthinned on shirts
Golden High Flow	Water	Up to 20%	25 to 50 psi
Tamiya acrylic	X-20A	Not given	Not given

Our thinning calculator turns these into drops for the amount in your cup.

How to thin in the cup, step by step

1. Shake the paint well. Pigment settles in dropper bottles.
2. Put the paint in first. Count drops into the airbrush cup; Vallejo's chart says to mix its thinner in the airbrush cup.
3. Add thinner in small steps. Createx says to add 4011 in increments of about 5% and only add more when you need better flow and atomization.
4. Stir, then wait if the maker says to. Createx asks for 10 minutes or more after adding 4011 so it acclimates with the paint.
5. Test on scrap at your working pressure. Spatter or a grainy spray means too thick; runs and spidering mean too thin or too close.

Mixing ahead and storage

Createx says its paints have no true pot life and stay sprayable for about 48 hours once reduced, but that 4011 speeds the loss of water, so only thin what you will use within 48 hours, keep bottles capped airtight, and avoid adding reducer to paint you mean to store. For automotive spraying, its hard-surface guide also strains paint before use (190 micron mesh for its paints).

Can you mix brands?

Makers write their instructions for their own products, and none of the ones we read endorses another brand's thinner. Water-based thinners are not all the same formula (Createx's data sheet lists propylene glycol monomethyl ether acetate, for example), so if you do cross brands, test the mix on scrap before a project. Never put a lacquer or enamel thinner into a water-based acrylic.

Thinner as a cleaner

Some thinners double as a flush between colors: Createx lists 4011 alongside water and its 5618 Airbrush Cleaner for rinsing colors out while you paint, and Tamiya says X-20A cleans away its acrylics. For end-of-session cleaning, use a dedicated cleaner; see airbrush cleaners and how to clean an airbrush.