Each color is different, so experiment to find the right mixture. Use newspaper strips to skim off any air bubbles from the size surface, and use an eye dropper to drop paint on the surface to test the consistency. If the paint expands slowly to a larger circle, it has the right consistency. If the paint sinks to the bottom, dilute the color with more water. For example, you can use a whisk to splatter paint on the surface, then swirl the paints to create interesting patterns.
Skewers also work well when swirling the paint.
The more paint dropped on the surface, the less white area will show. Be sure to rinse your tools under water before moving to the next color. When the desired pattern has been created, place the material down carefully on the surface of the size. Fabric - Drop the center first, then let the corners down gently. If this is your first time, you may want to have a friend help.