Powdercoating-Brass Discoloration

[Gordon]

I'm powdercoating brass cartridges-but can't seem to maintain the pre-baked finish on the finished cartridge.

The resulting discoloration isn't major - but it is noticeable.

Here's my steps:
1. Sand with micomesh 3200 thru 12000.
2. Brasso
3. Clean cartridge (inside & outside) with acetone.
4. Bake cartridge before powdercoating at 325 degrees for 20 minutes.
5. Apply Eastwood powder #10093-full gloss clear - at 15psi.
6. Bake cartridge at 325 degrees for 20 minutes.
7. Cool - 1 hour.

I wear laxex gloves and work in a dust free environment when handling the cartridges.

Not sure if I'm doing something wrong - or if my expectations are too high.

Would appreciate any comments

Thanks in advance.

Gordon

 

[jttheclockman]

The only discoloration I get is on the copper bullets. They get a shade darker than when first polished. To me it makes it look good so I have no problem with that. The brass should not change color or at least I have not experienced it. Maybe some else has better info for you.

 

[rherrell]

You'll always get a little discoloration but unlees you hold it next to an uncoated one the average person can't tell.
One thing jumped out at me, the pre-heat time. I pre-heat for just about 1 min., that's all. Just enough to get it warm so the powder sticks better. Also, your bake heat seems a little low. I use Columbia Coatings powder at 385 degrees for 15 min..
Your expectations might be a little high, mine were when I first started. You won't ever get a perfect finish like an uncoated casing but the trade off is EXCELLENT protection over a LONG time. I like the trade off.:wink:

 

[Sylvanite]

Gordon,

The normal schedule for Eastwood 10093 (full gloss clear) is 400F until flow-out and then cure at 350F for 20 minutes. Hot-flocking can reduce flow-out time, but your pre-heat time seems long to me. I'm surprised you don't get a lot of orange-peel heating to only 325F.

I've taken to using Eastwood 10329 (ultra clear low temp), which flows-out and cures at 340F. My schedule is to polish, wash with acetone, bake for <5 min (which drives off any residual acetone, let cool a bit, warm-flock at 10psi (15psi is higher than recommended for my gun), flow-out for 5 min at 340F, and then cure for 20 min at 340F.

My experience is that brass and copper discoloration comes from the heating. The higher the temperature and the longer the time, the greater the discoloration. Uneven heat sources (such as in toaster ovens) exacerbate the problem. I did some experimentation just heating uncoated cartridges before deciding that I needed a better oven and different powder.

Even so, I get a little discoloration. The brass is barely discernable, and the copper is noticably darker, but it still makes an attractive pen. When I need to preserve the bright pink color of freshly polished copper, I finish with brass-lacquer. When I want maximum durability, I powder-coat.

Regards,
Eric

 

[Gordon]

Thank you all - looks like I've got some adjusting to do.

Gordon

 

[wdcav1952]

Eric,

Thanks for the mini-tutorial. Yours was a very informative post.

 

[mick]

Eric your tutorial makes me .............to keep buying from you!
My powder coating set up has been sitting on a shelf for two years. maybe one day....lol