Powder coating getting darker.

[dahermit]

Using the same Harbor Freight Red powder, each time I powder coat a new batch via tumbling with Black and White Air Soft BB's the coating seams to be getting darker. I am using the same temperature (400 F.) and time (20 minutes). I noticed that even when the powder coat just begins to melt, (so it is not too hot of a temperature causing the problem), they are obviously darker than the ones I produced previously. The attached picture does not show the true shades of Red, but when looked at with the naked eye, the ones I am doing now are quite a bit darker. Anyone else noticed this or know what is going on?
155713

[Wild Bill 7]

I have the same problem. Last year my red was really red and shinny. Now it is darker and seems to be dull. Same powder different results.

[dilly]

What happens if you clean out your tub and clean your BB's?

[bangerjim]

Have you changed the time you BBDT? Remember, the longer you shake, rattle, and roll, the more lead is scuffed off and darker the coating will get.

That is why the use of a vibrator is NOT on my recommended list of how to BBDT. The violent and extended motion grinds off lead and darkens your coating. I had it happen EVERY time back when I was experimenting around. Leave your vibrator for cleaning brass.

My best results and recommendation: 15-20 seconds HARD swirl. Then ~10 seconds HARD up & down. That is all it should take. Longer will start grinding off lead and potentially darkening your lighter colored PC. And lead does easily wear off! You can easily write your name on a piece of paper with a cast boolit.

banger

[Schrag4]

bangerjim is right. I started out using my vibratory tumbler and without ASBBs, and I had the same thing happen - the coating got darker. I now spent a lot less time shaking/swirling in a Cool Whip tub with ASBBs, and I don't notice any difference in shade between batches.

[ebner glocken]

Jim is right, and I DO advocate using the vibrator for coating bullets. I have seen no effect of lead dust being suspended in the PC, it simply bakes in with the coating. If I lived in an area where humidity wasn't such a factor things would be seen differently. Way more than one way to skin this cat.

Ebner

[fredj338]

Pretty much follow banger on his method. Shake & swirl for about 30sec. If it's humid & HF red, maybe one minute. I bake for about 15min total, the red is pretty dark.
http://img.photobucket.com/albums/v703/fredj338/pc%20bullets2_zpss1jmukpd.jpg (http://smg.photobucket.com/user/fredj338/media/pc%20bullets2_zpss1jmukpd.jpg.html)

[AR15-SBR]

Are you guys using the same piece of parchment paper? I noticed the same thing after using the same piece of parchment paper several times. Started looking at the paper and it was VERY brittle...kind of came to the conclusion that the paper must be giving off some smoke that was darkening the paint. Went to NSAF and the colors came out more consistant.

Just my .02

AR15-SBR

[bangerjim]

My several racks with NSAF stretched on them (over Al roof flashing) last for a looooooong time! Many dozens of bakes. The boolits litteraly fall off when I tilt the rack after they are cool. No sticking. Not even any powder on the NSAF. I have never used parchment paper but I would think it would get brittle from repeated heating to 400F. Normal cooking/baking only goes to 325-350F, so 400 is pretty hot for the stuff. And the foodstuff (cookies etc) absorb the heat and the paper really never gets to 350 except at the edges and where there are no cookies.

But I have never seen any interaction between the NSAF and the powder as far as darkening. The only thing I have ever seen darken the powder is long vibrating/swirling and severe overheating (over 425F).

[Schrag4]

For me, parchment paper lasts about 10 bakes at 20min per bake before it gets too brittle. In my experience, boolits fall off of parchment paper - I slightly tip the tray and they all slide off. I reckon that one roll of paper will last me many years.

[brstevns]

I notice the HF red I have is always turning out darker and with less shine then pictures posted. What temp and time are you guys using it at?

[chrisstophere]

Is there a downside to a darker shade? I mean you're still coated and it's doing its job isn't it?

[brstevns]

I was just wondering why mine were darker that is all. They do shoot just fine.

[chrisstophere]

I was just wondering why mine were darker that is all. They do shoot just fine.
Okay cool. I just wanted to make sure I didn't neve to watch out for yet another thing.

[bangerjim]

A darker color will NOT interfere with the function of the PC as a lube!

Unless you bake the carp out of it and it is brittle!!!!!

banger

[Maximumbob54]

The oven gets too hot sometimes and over cooks the coating. Cheap ovens get hot spots in them and temperature spikes. One batch can be fine and the next may need to go back in if you dial it down too low or you may get browned bullets from the heat getting too high. I find my oven's sweet spot is about 375ish on the dial. It hardly ever over cooks anything and I've not had to heat it up again.

[dahermit]

A darker color will NOT interfere with the function of the PC as a lube!

Unless you bake the carp out of it and it is brittle!!!!!

banger
I guess it depends on what is making them darker. I suspect (as others have suggested), the my bullets got darker because I over-tumbled them (in a rotary tumbler) and the darkness is due to lead particles mixing with the powder coat paint. If that be true, and one keeps using the same air soft BB's and powder already in the tumbler, it will get darker and darker, with more lead in the coating instead of paint. So, theoretically at some point, the lead in the baked finish will somehow become problematic.

[bangerjim]

I guess it depends on what is making them darker. I suspect (as others have suggested), the my bullets got darker because I over-tumbled them (in a rotary tumbler) and the darkness is due to lead particles mixing with the powder coat paint. If that be true, and one keeps using the same air soft BB's and powder already in the tumbler, it will get darker and darker, with more lead in the coating instead of paint. So, theoretically at some point, the lead in the baked finish will somehow become problematic.


Don't use a mechanical tumbler (which it not needed), change the powder every so often, and wash your BB's.

Problem solved!