Does anyone have proven tips for preparing cold rolled 18GA sheet metal for powder coating? I have some light rust in areas after all the fabrication steps; that and I’m so slow it took me a while to get the fabrication done. The metal was newly purchased about 2 months ago so nothing severe. The last time I used the vapor hone, assuming it is even working, I had suffered with flash rust.
After scanning google search results for an hour or so I’m inclined to do the following:
- Lightly sand areas that feel rough to the touch or have a solid surface of rust
- Apply Klean Strip (TSP based) and scrub a bit with a steel brush
- Wipe it down with acetone
Any better suggestions?
Does the zep stop the flash rust? Last time I used the vapor hone the metal rusted in < 2 minutes. Do I need to immediately wipe it down with zep?
Depending on what kind of rust we’re talking you may be able to get away with one-step prep: do nothing.
Depends on how important the surface finish is to you, you’ll be able to tell but the powder will still adhere. Obviously if it’s flaking you’re going to have to remove it, I’d use a strip disc in an angle grinder.
I’m assuming with cold-rolled you don’t have mill scale. Mill scale will absolutely ruin your finish.
I was lazy and went over the paint/rust on this. It’s been outside for about 2 years since I coated it.
1 Like
I usually just blow it off with dry air when I’m done with each step. Our shop air is pretty dry.
1 Like
Do you use zep Purple straight or diluted? I’d rather use it straight because I’ll need to collect and store the used contents, then turn in to my city hazardous waste program.
Any degreaser will work fine. Zep, orange citrus. Even just soapy water is fine honesyly
The best way to prep any bare steel for automotive primer or powdercoat or anything else is sand it with a dual action sander and 80 grit paper. Then wipe with wax and grease remover, Acetone, or something else that will remove grease. Most people use a spray bottle and a clean rag
