CLEAR POWDER-COATING

FAQ'S RE: STEEL PATINAS & DYES — **Q & A**

Hello Bill.

I Have Had Awesome Results With RUST F/X, and use it frequently. I have had a couple bad experiences with putting clear powder coat on it—maybe 2 out of 10 times.

What appears to be happening is the Rust is out gassing during the PC process creating trillions of microscopic bubbles, creating a milky white affect in the PC over the rust. I have been doing a lot of testing lately and am learning more about it, but I thought I would ask you if you have run into this.

I have more testing to do, but what it is looking like so far is the treated piece needs to be pre-baked in the PC oven before applying the PC.

I have found no problems with clear paint.

Any thoughts?

Thanks, Dave.

Hi Dave,

[dropcap]A[/dropcap] couple of things come to mind, as I’ve run into the identical problem you’re mentioning, many years ago.

By the way…No Pre-Bake is Necessary…it will encourage Flash-Rust. Heat, Oxygen & Moisture are the 3 Main Elements of Ferrous Metal Oxidation, and Iron Oxide (Rust) is the enemy when Clear-Coating, No Matter What Clear You Use.

RUST F/X OR AUBURN F/X, ( the 2 Rusting Solutions I have) require copious amounts of water rinse, after you’ve reached the color range you want with the patinas. I usually mist the steel 3, 4 or even 5-6 times, letting it dry naturally, WITHOUT rinsing between applications.

But, after I have the color range (hue/colors/streaks/intensity, character, etc.), I rinse the hell out of it & let it Air-Dry. I don’t recommend Forced Air or Heated Air for doing this.

The white specks are the sulfides & salts from the chemical ingredients in both products. The patina doesn’t have a propensity to ‘off-gas’, during the bake-cycle, since there are no petroleum distillates or solvents involved in the formulae or in the process of applying patinas to steel.

Here’s the biggest single trick to know when powder-coating (or clear-coating) over a Rusted Patina: Go Over the Entire Piece ~ Front, Back & Sides, with a high-quality Tack-Rag, just prior to shooting on the powder or shooting the 2-Part Clear. Also, make sure that your steel is 100% dry, as latent moisture can also cause white specks or cloudy clear-coat.

Don’t use any solvents during the entire process, or you will have issues.

And, when Powder-Coating Clear, use the best quality powder you can get. I like a 100% Gloss Clear, but more importantly, keep your bake temp & cycle time to a minimum. When the Clear PC flows, take it out! And, whatever you do, (or have done by others), do NOT let the piece warm-down/cool-down inside the oven. A lot of Powder-Coating Companies do this, and it may be fine for PC over bare metal, but when Steel Patinas are involved, it is a Huge Detriment, With Absolutely Zero Benefit/s.

Let me know if this info helps, or if you have any further questions. I’ll be glad to help in any way I can.

Thanks,

Bill