Blurring is a nifty effect in painting. It can make the painted image look as if it's like a fast-motion photograph and imply rapid movement. You can blur a painting to soften the edges and make a soft focus image, suitable for certain types of portraits where you don't want harsh lines and sharp features. You can also blur an image to make it harder to read and add to the allure of a painting. The effect is employable both for realistic paintings, purely abstract paintings or any genre of painting in between. It can be done with either acrylic-based or oil paints. There are several methods, but the paint must not be dry.
Use a soft-bristled brush to gently push around the still-wet paint to soften lines and blur features. A stiff-bristled brush can leave marks. This mars the soft blurring. Sweep the brush across the image, from the area you want to stay untouched into the area where you want the blurring. The damp paint will carry with the brush and blend gently with the paint adjacent, creating even gradations. Sweep the brush back and forth to blend and blur two adjacent colours.
Place cling film over the area of the painting you wish to blur. Push the paint around under the cling film using the wooden spoon. Plastic spatulas or even your fingers are good tools to use, too. Use the tool size most suited to the area you want blurred. You can move large amounts of paint with this method. This produces more pronounced blurring than the subtle, soft-bristled brush. It is well-suited to abstract paintings.
Use a squeegee or soft scraper for photographic blurring effects. Ideally, the squeegee or scraper will be wide enough to do the whole painting in a single sweep, but you can do it area by area if you don't have a big enough tool. Softer tools are best, as they are less likely to leave marks in the wet paint. Lay the tool across the painting. Apply gently downward pressure. Pull the tool smoothly across the painting. The more pressure (and the wetter the painting) the more pronounced the effect will be.