Powder coating problem

[mofosheee]

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.

Cured powder strips off like that? News to me. I'll give it a try. Thanks!

 

[durableoreo]

I don't think the braze is the problem. Try low voltage around those areas and switch back to high voltage for the remainder

 

[RandyM]

I have applied 2 coats of powder to parts several times. Sometimes with a top coat of clear and sometimes with a top coat of color. I have never had a problem. I have also successfully applied powder and only half cured it, sanded it, and then final cured it to a perfect smooth gloss. I have even used the first coat to as a sand-able primer to fill in minor defects in the part to get a smooth finish. I had one part that was so rust pitted, I think I sanded and coated 3 times.

I also had problems with castings leaching oil when heated. The trick is to preheat the casting and burn the oil out of it first. I have applied powder with the part being hot and cold with good results.

Another option for you is to apply a primer coat. I have never used powder primers but it may be an option for you.

Getting powder to adhere to the part can be frustrating. Like Durableoreo mentioned, it looks like you may have a voltage problem. I have found lately that I do not pull the trigger of the gun to full on. Just crack the trigger for a very low pressure and powder flow. Hit the part with a fine cloud of powder.

Good luck, shoot us a pic of your problem. It would help immensely.

PS. I use the same gun as you do.

 

[mofosheee]

I'm thinkin that my o

I have applied 2 coats of powder to parts several times. Sometimes with a top coat of clear and sometimes with a top coat of color. I have never had a problem. I have also successfully applied powder and only half cured it, sanded it, and then final cured it to a perfect smooth gloss. I have even used the first coat to as a sand-able primer to fill in minor defects in the part to get a smooth finish. I had one part that was so rust pitted, I think I sanded and coated 3 times.

I also had problems with castings leaching oil when heated. The trick is to preheat the casting and burn the oil out of it first. I have applied powder with the part being hot and cold with good results.

Another option for you is to apply a primer coat. I have never used powder primers but it may be an option for you.

Getting powder to adhere to the part can be frustrating. Like Durableoreo mentioned, it looks like you may have a voltage problem. I have found lately that I do not pull the trigger of the gun to full on. Just crack the trigger for a very low pressure and powder flow. Hit the part with a fine cloud of powder.

Good luck, shoot us a pic of your problem. It would help immensely.

PS. I use the same gun as you do.

Hello Everybody
I would have to agree that my poor results are electrical in nature. With that said, I'm unable dismiss the fact that I suspended the part using stainless steel safety wire to my overhead garage door tracks as a contributing factor. No improvement was obtained by shifting the ground to a different location or using the hi/low voltage settings. All the basic application techniques and suggestions you mentioned were adhered to.
This is the first time I have attempted to powder over a "Tig'd" brazed part (and it didn't work)

My projects have always been quite satisfactory and consistent using my ghetto method.

With nothing to loose but time, I'm gonna attempt your "sand able" primer technique and powder over powder (thank you)
I'll go back and do it again.
Thanks everybody!

 

[C-Bag]

Wow, that really looks like faraday effect but I’ve never tried to powder coat brazed welds. Isn’t it weird the powder looks like it stuck to the middle of the braze weld but not the edges, or is it just the camera angle? Usually faraday effect happens when you have a deep crack between two pieces of metal. It looks like it doesn’t want to stick to where flux was but you tig welded it correct? So there is no flux, correct?

 

[mofosheee]

Wow, that really looks like faraday effect but I’ve never tried to powder coat brazed welds. Isn’t it weird the powder looks like it stuck to the middle of the braze weld but not the edges, or is it just the camera angle? Usually faraday effect happens when you have a deep crack between two pieces of metal. It looks like it doesn’t want to stick to where flux was but you tig welded it correct? So there is no flux, correct?

Hope this helps. You are looking at Silicon Bronze tig welded 4130, no flux used, not cast parts. Parts are 0.0625" wall thickness.
That's about a 3 inch run of bronze. The black (island) is elevated 4130 from an original part.
The blue arrow depicts the actual seam of the joint. The white arrow depicts where I used Silicon Bronze rod as a thin filler (cosmetic)
I put my best moves on it...........distance, flow, voltage, angles.

thanks again!

 

[RandyM]

I don't think you are doing anything wrong in your setup. This is a material issue with this brazing material and process. If you are not getting coverage during application there is no need to cure the powder. Multiple coats will not solve this issue. I guess I need more detail as to when this is happening, before or after cure.

Here is another half cocked idea that just popped into my head. You could also try using a demagnetizer before applying the powder.

 

[mofosheee]

Hello
It occurs during application and never made it to the cure phase. The powder is not sticking to the Bronze as does to the adjacent steel.
On one of my attempts, I grounded the part and started over. No change. I do not have a demagnetizer.

 

[RandyM]

Hello
It occurs during application and never made it to the cure phase. The powder is not sticking to the Bronze as does to the adjacent steel.
On one of my attempts, I grounded the part and started over. No change. I do not have a demagnetizer.

Well, demagnetizers are relatively inexpensive and worth a try at this point. The only other chance you may have is a primer, but that may be a low chance of success. You have pushed me to my limit on this one. You may also want to try contacting powder supplier for their expertise. I use Powder Buy The Pound. There are forums that you may want to check out also. Again, my guess is there is a charge in that bronze you need to get rid of. It is repelling the positively charged powder. Your process is good because you are getting good coverage of the powder on the rest of the part. Good luck.

 

[savarin]

My best results with powder coating came when I made a separate earth just for the parts.
I buried a copper pipe 1.5 metres in the ground and flood it with water when I'm coating.