Winsor & Newton Professional Acrylic Slow Drying Medium, 250 ml, Extends Open Time, Smooth Blends, Suitable for Longer Blending

By slowing the evaporation of water from the acrylic film, it keeps the paint workable longer on the palette and on the canvas, allowing you to blend colors smoothly and create soft transitions without sudden drying or caulking rims.

250 ml bottle. Extends working time, enabling wet-in-wet gradients and soft transitions. Edge control helps reduce dry rims on broad flats. Preserves film integrity when used at recommended ratios. Can be mixed with colour or diluted with water sparingly. Helps counteract rapid drying under warm studio lights. Dries clear in the paint layer.

Begin with a small amount and test on a palette or scrap surface. A typical starting point is a few percent of the total mix (adjustable up to around 5–15% depending on the desired open time). Add gradually to your paint until you reach the preferred working time. If diluting with water, do so sparingly to avoid overly weak film strength.

Yes, it can be mixed with acrylic colours or lightly diluted with water. Avoid excessive dilution or over-mixing, which can weaken film strength. Always test on a sample surface before applying to a final piece.

Ideal for glazing, soft gradients, large flat areas, and any technique requiring extended blending time. It is particularly helpful under warm lighting or in studios where faster drying is accelerated by heat.

Work while the paint is still within its extended open time, using gradual, even strokes and blending along the edges. Maintain a slightly damp brush or palette and blend from mid-tones to edges to reduce visible rims.

Rinse brushes and tools with warm water and mild soap after use. Wipe clean and reshape bristles. For dried traces, a gentle brush cleaning followed by a rinse helps maintain brush life.

As a water-based acrylic additive, it is non-toxic and designed for studio use. Store in a cool, dry place with the cap tightly closed to prevent evaporation and contamination.

Yes. Once the acrylic layer has fully cured/dried, you can apply varnish. Ensure compatibility with your chosen varnish and test on a sample area if possible.

If you’re evaluating alternatives on Fepy, you might consider: 1) Winsor & Newton Flow Improver, which enhances flow without significantly extending open time: https://fepy.com/product/winsor-newton-professional-acrylic-flow-improver-125ml 2) Winsor & Newton Fluid Matte Medium, which adds a matte finish and can affect drying time subtly: https://fepy.com/product/winsor-newton-professional-fluid-matte-medium-250ml 3) Winsor & Newton Glazing Medium, designed for glaze consistency and layering: https://fepy.com/product/winsor-newton-professional-acrylic-glazing-medium-200ml These options offer different blends of flow, finish, and open time, so your choice depends on the effect you’re aiming for.

Professional artists and serious hobbyists who rely on smooth gradients, extended blending, and controlled edges will benefit from the extended open time. The investment pays off in improved control and fewer hurried brushstrokes, especially for large canvases and detailed blending work.