Winsor & Newton Professional Acrylic Slow Drying Medium 125ml — Doubles Open Time, Preserves Colour

This slow drying medium is formulated for Winsor & Newton Professional Acrylics to extend open time while preserving colour, viscosity and finish. Artists who need extra blending time for glazing, soft edges or complex transitions will find this 125ml bottle useful: at a 1:1 ratio with paint it roughly doubles drying time, yet it leaves no visible colour shift once fully cured. The medium mixes smoothly with acrylic colour and keeps handling predictable so techniques developed with standard acrylics remain intact.

How does the slow drying medium change working time and blending?

The medium retards evaporation of acrylic water and slows polymer coalescence, giving you more time to blend wet edges and develop gradual transitions. Using equal parts medium and paint (1:1) approximately doubles the drying time; smaller additions produce proportionally smaller extensions of open time.

• 1:1 ratio of medium to paint doubles drying time
• Add in smaller increments to fine-tune open time
• Useful for glazing, feathering edges, and wet-on-wet blending

Will this medium change my paint’s colour, sheen or viscosity?

The formula is designed to maintain the original colour and viscosity of Winsor & Newton Professional Acrylics. When the paint dries, there is no perceptible colour shift and the finish remains consistent, so your colour mixes and layering strategies stay reliable.

• No colour shift from wet to dry when used with the brand’s professional acrylics
• Maintains paint viscosity for familiar brush handling
• Preserves the intended finish of the acrylic film

How should I mix and apply the medium for best results?

Pour the medium into your palette and mix thoroughly with paint until uniform. Start with small proportions and test on a scrap surface—work in 1:4 to 1:1 ratios depending on how much extra open time you need. Apply with brushes or palette knives as normal; allow adequate drying time between layers when building multiple glazes.

• Stir or mix well to fully combine medium and pigment
• Test small swatches to evaluate drying time and finish
• Use standard brushes, knives or airbrushes compatible with acrylics

How do I store and handle the 125ml bottle safely?

Keep the bottle tightly closed when not in use and store upright in a cool, frost-free place away from direct sunlight. Clean tools immediately after use with water; discard excess medium per local disposal guidelines. Proper sealing ensures the medium retains its performance over time.

• Store upright, sealed, away from heat and freezing
• Clean brushes and tools with water while wet
• Follow local rules for disposal of excess product

Who is this for: The Winsor & Newton Professional Acrylic Slow Drying Medium (125ml) suits professional painters, fine art students and hobbyists who need controlled extra open time without compromising colour fidelity or handling. It’s ideal for artists working in glazing, soft-edge realism, landscape transitions, or any technique that benefits from longer working sessions with acrylics.