Gum Arabic is a pale coloured water colour medium that is used to increase the brilliance, gloss and achieve areas of transparency. Adding Gum Arabic to your water colour has three effects: it slows down the drying time of the paint allowing for increased workability, giving you slightly longer to work on creating your image or working wet into wet; it adds further transparency to your water colours and it increases gloss. Gum Arabic washes will have greater depth and appear more luminous than colour washes alone.

Gum Arabic is usually mixed into the water colour wash but can be added to the jar of water if you prefer to use it throughout the painting. Gum Arabic should not be used directly from the bottle because thick films will be brittle.