Powder Coating Troubleshooting Guide
Chapter Five: Measuring Up the Product
Calculating Specific Gravity and Why It Affects Coverage
ABC Fabrication is getting a price on coating 120,000 sq. ft. of sheet metal from two different companies using a film thickness of 2.25 mils.
Company X is asking $2.28 per pound, and Company Z is asking $2.58 per pound. At 30¢ less per pound Company X is 12% lower and appears to have the better price. But look closer.
Company X price is $2.28/lb and SG=1.68
Company Z price is $2.58/lb and SG=1.28
So the real savings is with Company Z, $778 in material costs. It continues to add up, 576 fewer pounds of powder means less freight costs. And since there is less powder there is less time and wear on the spraying machines. Specific gravity is an important factor in determining coverage and cost per square foot.
Though powder is purchased by the pound it is applied by volume. Therefore purchasing powders with a lower weight per volume will coat more square footage of substrate.