All of our paints are sold RFU (ready for use). This means there is no need to add anything to the paint. 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 as 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 exact reduction ratios will vary depending on the formula. Meaning some colors will be at 20%, while others may be at 10% reduction.
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.