Powder coating problem

[mofosheee]

Hello Forum

Powder coating issue on a cylindrical; 0.062" x 1.5" x 24" Chrome Moly pipe with two perpendicular attachments brazed on.
The powder coating over the brazed areas on 1/16" chrome moly pipe has been marginal indicated by poor build up or adhesion to the part while the un-brazed areas turned out rather well. I am using an Eastwood kit (similar to this;

Eastwood HotCoat® PCS-250 Dual Voltage Powder Coating Gun

Using standard 120-volt household power, the versatile and economical PCS-250 dual-voltage powder coating gun is the perfect solution for a variety of projects.

www.eastwood.com

) and Eastwood powder.
How well does powder coat stick to previously applied powder coat please?
I appreciate all suggestions.

Thank you!

 

[C-Bag]

What did you do to clean the brazed area before powder coat?

 

[stobl]

Best bet is to completely strip it again/ sandblast and recoat. Sounds like the brazing joint wasnt fully clean. Sandblast, bake it to get out any oils/ clean with brake cleaner, acetone, etc.

Blake

 

[C-Bag]

Even my hi $$ powder coat unit doesn’t recoat very well. Best bet is do like stobl suggests. Powder coat is not much fun to strip

 

[mofosheee]

What did you do to clean the brazed area before powder coat?

Sandblast followed by acetone

 

[C-Bag]

Personally I hated the finish with sandblast then powder coat. Bead blast was much smoother and nicer. Did you wipe on the acetone? I mean both should have worked(sand and acetone) but powder coat just like paint is all about the details. Maybe if you wiped on the acetone it transferred contaminants instead of wiping off, just spitballin’ here. I use brake cleaner in a can. Thought about acetone in a pressure can but hate to mess with what works as if it doesn’t, it’s a mess to redo.

Where was your ground hooked to? The main piece that came out good? Maybe try the ground on the perpendicular piece?

 

[mofosheee]

Personally I hated the finish with sandblast then powder coat. Bead blast was much smoother and nicer. Did you wipe on the acetone? I mean both should have worked(sand and acetone) but powder coat just like paint is all about the details. Maybe if you wiped on the acetone it transferred contaminants instead of wiping off, just spitballin’ here. I use brake cleaner in a can. Thought about acetone in a pressure can but hate to mess with what works as if it doesn’t, it’s a mess to redo.
Where was your ground hooked to? The main piece that came out good? Maybe try the ground on the perpendicular piece?

The finish was acceptable and met my expectations (except where the powder failed to stick) The powder wouldn't stick / grab onto the bronze. The part was grounded to the main frame. In my reasoning, electrical continuity had to exist everywhere otherwise I couldn't have brazed it.

I wiped with what I thought to be a clean acetone soaked rag. But, if I "transferred contaminates" ............. wouldn't I have transferred contaminates everywhere? Yes, I have previously used brake cleaner before with no issue. I'll be sand blastin for a redo very soon.

 

[derf]

If you can't get consistent static cling, you can heat the part first. Stripping powder off is a pain even with a blaster. When I make mistakes and have to strip, I soak a paper towel in carb cleaner, wrap the part with it and put in a plastic bag so it doesn't evaporate. In about 20-30 min, it will peel off like grape skin.

 

[C-Bag]

I soak a paper towel in carb cleaner, wrap the part with it and put in a plastic bag so it doesn't evaporate. In about 20-30 min, it will peel off like grape skin.

Good on, never thought of that. I got some powder coat stripper that is non toxic and it works wonderfully, but very expensive. Luckily I don’t have to strip but once in a blue moon.

Trying to figure out blind and long distance what is going one with OP’s job more spitballs came as I was coincidentally powder coating today. There are so many details like just mentioned about temp. I have rack on top of my oven that sits out in the sun and I keep parts on before the final hosing with brake kleen to get them warm. I’m also super careful about outside humidity and temp as I powder coat with my garage door open. I don’t coat if it’s less than 65f and less than 10mph wind. I have a special 24” square powder booth with a carousel rack in the middle for parts. It is isolated electrically from the booth so the ground is only on the carousel/parts. All of these helped incrementally improve my coat depth. I also started with an Eastwood gun and the power supply got weaker and weaker leaving more powder on the bottom of the booth and less on the parts. The new pro unit also has a faraday setting for parts with lots of structure. Works great. I also went on to using powder from a regular company, not Eastwood.

 

[woodchucker]

Hello Forum

Powder coating issue on a cylindrical; 0.062" x 1.5" x 24" Chrome Moly pipe with two perpendicular attachments brazed on.
The powder coating over the brazed areas on 1/16" chrome moly pipe has been marginal indicated by poor build up or adhesion to the part while the un-brazed areas turned out rather well. I am using an Eastwood kit (similar to this;

Eastwood HotCoat® PCS-250 Dual Voltage Powder Coating Gun

Using standard 120-volt household power, the versatile and economical PCS-250 dual-voltage powder coating gun is the perfect solution for a variety of projects.

www.eastwood.com

) and Eastwood powder.
How well does powder coat stick to previously applied powder coat please?
I appreciate all suggestions.

Thank you!

Powder can't be applied on powder, simply because you can't get a connection through the powder that's already baked on. It's basically plastic, so an insulator. But if you could then it would bake in no problem...
So strip it and start all over. Try acetone as powder really fouls grinders sanding wheels.