Powder coating coverage and transfer efficiency
Powder usage is simply film volume times density. The industry form of that relationship is coverage (ft²/lb) = 192.3 ÷ (specific gravity × mils), where 192.3 ft² is what one pound of an SG 1.0 powder would cover at 1 mil. A typical SG 1.5 powder applied at 2.4 mil therefore covers about 53 ft² per pound before any overspray is counted.
Transfer efficiency decides what you actually buy. A corona gun spraying to waste commonly lands 40 to 70% of the powder on the part, while a booth with cyclone reclaim pushes effective utilization above 90%. Size your purchase on first-pass efficiency without reclaim and treat recovered powder as a bonus rather than a planning assumption.
Entering the powder you actually used back-calculates real transfer efficiency against the theoretical figure. If it comes out far below plan, check gun voltage and powder output, part grounding, hanger spacing and part geometry first — deep recesses and Faraday cage areas drop efficiency even on a well-tuned line. Follow the powder manufacturer data sheet for specified film build and cure schedule.
Frequently asked questions
It is listed as specific gravity or density on the powder manufacturer technical data sheet. Common polyester powders fall near 1.4 to 1.7, but pigments and fillers shift it, so use the value for the exact product.
Reclaim raises effective utilization sharply, but the number depends on how much recovered powder you blend back in. Back-calculate it from monthly powder consumption against square footage coated rather than guessing.