Watercolour paint is a paint medium that consists of using pigments suspended in a water-soluble vehicle. Watercolour is often used on paper, vellum, plastics and canvas. Watercolours come in different forms; some are squeezed out of tubes, some are in small block forms. In all forms, gently mixing with water is necessary before painting. If the paint seems to thin, or watery, there are several steps you can take to thicken the watercolours.
Pour more paint unto the palette. If you already began to paint and added too much water to your paint, the solution is to simply put more paint onto the palette and mix with the existing paint. Excess water is often introduced if you do not dry off your paintbrush sufficiently after cleaning. Squeeze additional paint into the thinner paint and use a brush to gently mix together.
Add in a paint thickener. Paint thickener for watercolours can be found at your local hobby store. Different types of paint thickener are available, including a silicone based gel product that ensures your colour does not change, as well as a gum paste variety. Add a small amount to your watercolour paint and use a paintbrush to mix together.
Check the consistency of your paint by brushing a small amount onto a piece of cardboard or paper. If the consistency is still slightly watery, continue to add paint thickener in small amounts until the desired consistency is reached.