[TheForge] Outdoor Finish

[RIES NIEMI]

There is no magic bullet for finishing mild steel for outdoors.

I have powdercoated literally thousands of pieces- for indoor use.
Powdercoating just wont hold up outside, no matter what they tell you.
Most colors will fade in the sun within a year or two. Some of the grays and
blacks will get white spots from uv. The so called "zinc rich" primer does
not act as a galvanize would- there is just not enough zinc in it, and the
zinc particles are suspended in powder, so the electrolytic process doesnt
work right. I have a sample piece of railing, powdercoated black wrinkle,
outside my back door. I put it up in about 96, and there is no rust or
peeling, but it doesnt look very good after all these years. It is the type
of powder that is supposed to do best outside, and frankly it is not
something I could recommend to a customer. Green mold grows pretty good on
it, though.
 
If you want a painted finish, one way to go is sandblast, galvanize, and
then paint. Of course, the galvanizing adds a syrupy thick coat to the
metalwork, which may obscure fine detail.

The classic ironwork in Europe was mostly wrought iron to begin with, and
then repainted on a regular basis by low cost servants. Using mild steel,
realistically you need to plan on in place sandblasting and repriming and
painting every 10 to 15 years.

This is one reason I have been doing a lot of stainless steel in the last
few years for permanent outdoor work.

Ries