Q: How many microns are required in powder coating on normal metal sheet or aluminum?
A: The thickness of powder depends upon how much durability is needed. As a general rule, a minimum of 50 microns (2.0 mils) is a good idea for indoor applications; 60-75 (2.4-3.0 mils) microns are even better.
For more demanding decorative environments, 75-100 microns (3.0-4.0 mils) may be needed. And for functional applications such as steel reinforcing bars and pipeline coating, 200 to over 400 microns (8.0-16 mils) thickness is common.