“Is a single coat of powder coating over mild steel (14 ga. tube) sufficient for corrosion resistance for an outdoor application? The finished product is a fence.”
“You better have a detailed specification written for the person coating this fence product otherwise it may not perform as well as you would like. This specification would detail pretreatment, primers, topcoats, etc. to ensure a 20 year life on steel. A single coat of powder over mild steel without proper pretreatment, primers, etc. may only last one to 5 years.
However, an outdoor durable powder topcoat over the right primer and pretreatment can give you 10 to 20 years, or more life, depending upon the part of the country it is installed. A good pretreatment and a single coat of powder over aluminum can provide 20 years life, easily. I hope that this helps. Oh, by the way, we write these types of specs all the time for our clients.”