Q: Can a steel powder-coated insert work inside pressure-treated lumber? This is for an outside fence where I have a decorative steel insert placed into a pressure-treated fencepost.
A: I think I understand your question. It sounds like you wonder if a powder-coated steel item that has been inserted into pressure-treated lumber will withstand the elements.
There are at least a couple issues. Is the powder UV durable? And will the powder resist the nasty chemicals that are present in the pressure-treated lumber?
As for the first question – the powder will resist fading, chalking, and corrosion if it is a good-quality polyester or polyurethane powder. Hybrids and epoxies will chalk and fade if exposed to sunlight.
Now for your second question – the powder will probably resist the pressure treatment chemicals. It’s important to ensure that the steel is clean and chemically pretreated before applying the powder coating. Unclean steel will compromise adhesion and corrosion resistance. Pretreatment (iron phosphate or zirconium) will enhance adhesion and corrosion resistance more so. You also need to ensure 100% coverage of the steel. Voids in the coating provide excellent sites to propagate corrosion.