[TheForge] Outdoor finish, rust protection

[Ries Niemi]

I forge stainless all the time- you just have to go cyborg- that is, 
replace your arm with a mechanical one. In my case, a power hammer. 
Remember- once youve tried cyborg, you never go back!
Actually, I do a fair amount of hand forging on stainless as well, and 
as long as you are working in the hot zone, it is not too bad. It seems 
to cool faster than mild, so it takes more heat, though.

As far as the ideal outdoor finish- this question has no good answer.

In the old days, the answer was use wrought iron, and then employ low 
salaried menials to repaint every few years.
Neither of those options is available to most of us anymore.

Mild steel rusts. Its just a matter of time.
A lot of people sandblast first, then hot dip galvanize, then prime, 
then at least two coats of a good industrial enamel. This works pretty 
good. It is expensive, time consuming, and it fills in a lot of detail. 
But if you have to guarantee a painted finish, this is the way to go.

I mistrust most "zinc rich" primers, as the zinc is encapsulated in the 
paint, or powder coat, as the case may be. This means it cant do its 
sacrificial thing unless the paint totally breaks down first. Only a 
zinc paint that is somewhere around 90% zinc will work as a cold 
galvanized finish. Hot dip is much better, but when you get it back 
from the galvanizer, expect a lot of cleanup- in fact, we were doing 
some of that today- filing off drips, sanding out sharp edges, and 
generally cleaning up after the "dripped in honey" look.

As far as powdercoating outside goes- I know, some people swear by it, 
but me, I dont trust it.
I have had literally thousands of pieces powdercoated, but for inside, 
not outside use. I have a test running right now- I built a little 
handrail for my back porch, probably about 9 years ago- had it 
powdercoated black wrinkle. So far, no peeling. It does have a good 
layer of some kind of green organic substance growing on it, though.
But I have seen powdercoating in direct sunlight fade within a year, 
and it is not very impact resistant- one good bang, and it starts to 
peel. And then you cant touch it up on site- you gotta pull the whole 
thing out, bake the powder off, sandblast it, and start over.

So for steel, I say- sandblast, galvanize if possible, prime, then 
paint. Use the best paint you can find. I have had good luck in the 
past on smaller things like chairs with catalysed polyurethanes- you 
mix it up, and you have an hour or two to spray, then clean your gun, 
and then, zap- it goes off, and its like epoxy. I didnt do this myself- 
I sent it out to a place that, after spraying, rolled the carts into a 
500 degree oven to set the paint. That stuff is pretty tough.

But just remember what neil young says- rust never sleeps.

ries