Longevity of Clear Powdercoating

[Pres10]

I've started using clear powdercoating as a finish for outside steel
sculpture. I like the look of metal that has natural character from either factory forge marks or distress.(end pieces, roll marks, pits from old rust, etc.) I like to clean with wire wheels etc. to get a nice metal look that isn't grinded. Ive also started torching texture. In the past once I've gotten what I want for a finish, I would use clear-coat paint, but the finish would start breaking down (on outside pieces) after a couple years. (or sooner)
I've only been using the powdercoat process for a year or so and was wondering if anyone out there has pieces that have been clear powdercoated for 5 or more years? If so how has the finish held up? My concern is over the fact that, as I understand it, you can't do much if powdercoating starts to deteriorate. Thanks for any imput.
Preston Fennell

[Araich]

Hi Pres10, I used clear powdercoating over brushed (very clean) steel some 8+ years ago, on a number of works, one of which has sat in the damp shade of my backyard ever since.

First off, powdercoating is not a perfect seal (what ever they may say). And as such, fine tracks of rust will appear like webs as the perosity allows air and moisture in to corrode.

Secondly, any knock to the surface will cut to the metal, and away goes the rust from that point.

Without a perfect seal, and/or a galvanic protection, the steel will find a way to rust.

The good news? It happens slowly, and if inside, or dry, I've seen work remain completely rust free - but this has also been polished steel (no original rust).

One material that has been very good inside, is Penetrol - "with a penetrating ability 3 times that of water" it displaces moisture and with several coats creates a nice varnished look. It is a paint conditioner but applies like a thin clear coat, and dries fast. I recommend drowning small complex works over a tray, as the first coat, then brush further ones.
And better still, it is easy to patch/apply further coats.

Unfortunately, in my own efforts against rust, I have left behind clear coating, and now shotblast/hot zinc/paint.

I just couldn't stand the thought of all those works returning down the line.


A penetroled work:

[sculptorsam]

Very nice piece, Araich. Do you need to reapply coats over time to maintain it? Yearly perhaps?

Rust will always find a way. I recently saw an indoor piece that had been powder-clear coated about 6 months ago or so and already I could spot the tell-tale spider lines of incroaching rust. I got fed-up trying to fight the inevitable a while ago and switched to Cor-ten steel. If you can't beat 'em, join 'em!

Sam

[Araich]

Originally posted by sculptorsam
Very nice piece, Araich. Do you need to reapply coats over time to maintain it? Yearly perhaps?


Thanks Sam, that's an old work for me.
Nope, if the coating is not damaged, you can more or less treat it as if it has been painted. i.e. place and forget.

I also had some success with an anti corrosive that was made for aeroplanes. It penetrated, leaving a thin (8 micron or something) film protectant. It was clear with a yellow tint, and you could paint a clear top coat over.

Another one I liked, was penetrol first (thinned and dip the work + brush coat) then spray a matt acrylic. It leaves the steel looking like leather.

I'd often also use Blue Gun Metal (http://www.ssschemical.com/bluegun1411.htm) chemicals to darken the polished steel - but watch out you wipe it all off with turps or something, or else it will rust the steel under the clear coat.

Mild steel/wire brushed/gun metal blue/penetrol/matt acrylic:

http://www.artwise.com.au/hague/images/theytango_hague_side_600.jpg

[sculptorsam]

Those finishes sound so nice, I may just be tempted to do some indoor work. I just hate the plastic-like feel of paint on metal. But you seem to have gotten around that with even an increase in longevity.

Sam

[Pres10]

Thanks for the imput...I've noticed some of the beginnings of corrosion on some of the pieces that have been outdoors for 6 months or more. Minor, around welds or in crevices. Still wish I could get a finish on steel that looks natural and lasts outside for long term. Thanks...keep sparkin. Preston.

[gregmueller]

Great Conversation--
Steel is a beautiful material--and I agree with Sam--how do you celebrate it without a plastic coating?
I just purchased "Permalac" a clear coat for ferrous metals from Peacock Labratories in Philadelphia--they say it is great stuff. Obviously too early to tell---I think they sell the Incralac too that Ron Young suggests on his web site--for bronze.

Greg Mueller

[sculptorsam]

Hey Greg, great to see you on here. Keep us posted on how the Permalac holds up.

Sam

[fritchie]

I'm speaking with no experience here, but am repeating word of mouth. On the earlier ISC discussion board about 3 years ago, several people who evidently had used it, said Incralac has to be removed and renewed about every year or two. I guess this depends on the weathering conditions, and in dry environments it might last longer.