Electrostatic Spray Calculator

Theoretical coverage is directly proportional to volume solids: sq ft/gal = 1604 × %solids ÷ DFT. A coating with 70% volume solids leaves nearly twice the dry film per gallon sprayed as one with 35% solids at the same target DFT, because more of what's in the can is solid material rather than solvent that flashes off. This is why comparing coatings purely on price per gallon can be misleading — a higher-solids product often covers far more area per gallon.

Dry film thickness (DFT) is what you're actually trying to achieve — the cured coating thickness that provides protection — but it can only be measured after the coating dries or cures. Wet film thickness (WFT) is what you can check with a wet-film gauge during application, calculated here as DFT divided by the volume-solids fraction. Since some of the wet film's volume is solvent that evaporates, WFT is always higher than the DFT it's targeting.

Electrostatic guns impart an electrical charge to the atomized paint particles, which are then attracted to the grounded, oppositely-charged workpiece rather than drifting past it as overspray. That's why the calculator models electrostatic transfer efficiency at 65-85% versus 30-40% for conventional air spray — more of the paint you spray actually lands and stays on the part instead of becoming waste.

The calculator flags a Faraday cage risk whenever charging voltage exceeds 70 kV and target DFT is below 1.5 mils — a combination where the strong electric field around the part can actually repel paint from deep recesses, inside corners, and cage-like geometry instead of pulling it in. It's a known limitation of electrostatic spraying on complex shapes, and this tool can only flag the risky input combination, not correct for your specific part's geometry.