All our paints are sold ready for use (RFU) ready for use. You can literally put it in the gun and spray. Some painters will have preferences on the viscosity of the paint flowing through their gun, or they may be trying to "stretch" the amount of paint in a container. These practices are NOT recommended; it can have negative effects on the paint. The paints are engineered to work a certain way so we ask that you not modify the formula.
The only additive that would be needed is the catalyst for our professional size clear coat and primer. The catalyst ships in a separate container and will be at a 4:1 mixing ratio. All catalysts are pre-measured, but it's a good idea to double check before mixing.