Coverage of Powder

Q. I would like to know the best method to measure the coverage of a powder in a production line. A local supplier tells me that his powder will cover 14 sq m/ kg, but I need to reproduce this figure in the process line. I appreciate it if you can help me. L.T.

 

A. Powder materials will cover 192.3 sq ft/lb at 1.0 mil thick with a specific gravity (density compared to water) of 1.0 and 100% utilization (approximately 39.8 sq m/kg). If you factor in the specific gravity, actual film thickness and production efficiency, you will get the real online number.
For example, say the power has a specific gravity of 1.5, you apply an average of 3 mil and you collect the overspray for reuse so your material utilization is around 95%.

 

39.8 sq m/kg × 0.95 (material utilization) = 37.8 sq m/kg

37.8 ÷ (1.5 SG × 3.0 mil) = 8.4 sq m/kg

If you cut the film thickness to 2.0 mil average, your coverage goes up to 12.6 sq m/kg. If the specific gravity is 1.4, and your thickness is 2.0 mil 13.5 sq m/kg.

You can adjust the input variables and get different results. If you do not reuse overspray, the coverage goes down a lot, and if you apply thicker films it goes down a lot. No one can claim that their powder will cover a certain area without factoring in the variables.