Create a new layer then fill with white. You must fill the background with white; this will not work on a transparent layer.

Set the foreground color to black. If you use any other color, the blood splatter will look flat. Select the brush from the brush palette (Window > Brushes) then click on the document window where you like to place the brush.

Choose Image > Adjustments > Hue/Saturation. Checkmark the colorize option then apply the settings shown below. You can also change these settings to alter the color. For example, setting the lightness to around 20 can give it an acrylic paint look.

In the Styles palette (Window > Styles), click on the flyout menu on the top right then choose Load Styles.

Click on the White Background layer style. This will make the white areas of the layer transparent; just like using a brush.

