Acrylics dry fast. That is great for layering and terrible for soft blends like clouds, skin or sunsets. Painter Greg "Craola" Simkins slows his paint down with a homemade medium: equal parts acrylic retarder and a slow-dry matte liquid, kept in a labeled squeeze bottle. In this demo he coats a dark canvas with it and blends a cloudy sky that is still wet after ten minutes of working.
What acrylic retarder does
Retarder slows the evaporation of water from acrylic paint, which gives you more "open time" to push, blend and soften. It does not thin the paint the way water does. Slow-dry mediums do the same job with added body. Greg found the 50/50 mix gave him plenty of blending time but still dried in roughly 10 to 15 minutes once he stopped.
When retarder helps most
Reach for it on soft skies, portraits and sunsets, anywhere one color has to fade into the next without a hard line. It also helps on hot, dry days or outdoors, when paint skins over on the brush in minutes. For crisp graphic shapes or fast layering, skip it and let the quick drying work for you.
How to use acrylic retarder without overdoing it
More is not better. Greg's first try was a thick coat of straight retarder across a whole background. A day later it was still wet, and the paint kept lifting when he tried to work over it. He had to wipe off what he could and seal it with matte medium before he could go on. Start with a small amount, follow the label's maximum, and test on scrap canvas first.
Ways to slow acrylic drying
| Method | How it helps | Watch out for |
|---|
| Retarder | Longest open time on the canvas | Too much stays tacky for days |
| Slow-dry medium | Open time plus a little body | Changes sheen slightly |
| Wet palette | Keeps paint fresh on the palette | Does nothing once paint is on the canvas |
| Misting with water | Quick and free | Thins paint and can drip |
Brushes and blending tips
- Keep the blending brush dry. A wet brush lifts the paint instead of softening it.
- Use one brush per value. Greg keeps one for the brightest highlights, one for white and one for mid-tones so colors don't get carried across.
- Cheap brushes are fine. He uses inexpensive chip brushes from the hardware store for this kind of scrubbing and badgering, since it wears them out.
- Go light. Barely touch the surface. Pressing hard digs up the layer underneath.
Label your bottle
A slow-dry medium in a white squeeze bottle looks exactly like white paint. Mark it clearly so you never add white to a painting when you meant to add medium, or the reverse.
Keep going
Put the extra open time to work with how to paint clouds and how to blend acrylic paint. For thin transparent layers, see how to glaze with acrylics. If your paint is too stiff rather than too fast, try how to thin acrylic paint.
