For a sharper, more visible brush stroke, add Amsterdam thickening medium to your paint. Create a luscious, thick consistency by adding just a small amount of this medium to your Amsterdam acrylic colors. This medium does not affect the color intensity or opacity of the paint since you only need a small amount.(br /) (br /) How to use:(br /) (br /) Use a painting knife to thoroughly mix a small amount of the thickening medium with your paint. After this, you can paint with a brush. Be careful not to use too much of the thickening medium, this will result in rubber or gum-like paint that is unusable.