How much gel medium should I add to acrylic paint?

A typical ratio is 1:1 (equal parts gel medium and paint). This extends the paint volume and builds body while maintaining colour intensity. For glazes you switch to a fluid glazing medium rather than gel: Liquitex recommends roughly 1 part Soft Body colour to 10 parts glazing medium for a transparent glaze, so the colour becomes much lighter and more translucent.

Can I add too much retarder to acrylic paint?

Yes. Retarder has no acrylic binder, so too much weakens the dried film. As a working guide keep it to about 10-15% of the paint volume; Liquitex (Slow-Dri) permits up to 25% by volume but states you must not exceed that, otherwise the paint may stay tacky and never fully cure. A little goes a long way, so start low.

What is the difference between flow improver and water?

Flow improver reduces surface tension so paint flows and levels better without weakening the paint film. Water dilutes the binder (acrylic polymer), which above 30% can cause the dried paint to be chalky, crack or fail to adhere. Note that a concentrate such as Liquitex Flow Aid must first be diluted with water (around 1 part Flow Aid to 20 parts water) before it is added to paint — used neat it causes poor adhesion and cracking.

What is pouring medium?

Pouring medium is designed for fluid art techniques where you pour paint across a surface. A 2:1 ratio (medium to paint) is a common starting point for a self-levelling consistency while maintaining colour vibrancy and a strong paint film. Products like Golden GAC 800 and Liquitex Pouring Medium are used in this range, so adjust to the runniness you want.

ArtCalcs

Acrylic Medium Calculator

Work out how much gel medium, retarder, flow improver or glazing medium to add to your acrylic paint.

Paint Volume

How much acrylic paint you are starting with, in millilitres

Medium TypePick the additive — each carries its own recommended ratio

How We Calculate This

Medium needed = (Medium ratio / Paint ratio) × Paint volume

Recommended ratios

Gel medium: 1:1 (equal parts) to extend and thicken
Retarder: ~10-15% of paint volume (Liquitex permits up to 25%, never more)
Flow improver: up to 25% of paint volume — dilute concentrate (e.g. Liquitex Flow Aid) ~1:20 with water first
Glazing medium: 10:1 (medium to paint) for a transparent glaze
Pouring medium: 2:1 (medium to paint)

Ratios follow Liquitex and Golden product guidance. Retarder and flow improver contain no acrylic binder, so respect the manufacturer ceilings to avoid a weak or tacky film.

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Last updated: February 2026

All calculations are estimates. Always verify quantities before purchasing materials.