Powder coat issue

[hornetguy]

I don't want to sidetrack another thread, so I thought I'd ask here..
I have two double bagged bags of powder I've had for several years, kept out in the garage workbench storage.
I tried to coat some bullets the last two evenings, with almost zero success. This powder coated pretty well when I bought it.... can't remember exactly who I bought it from... I think it was Powder by the Pound, but can't be certain...

These bullets were cast about 2 days prior to attempting to coat. They have not been handled, just sitting in the little plastic bullet boxes I put them in.
I have a bowl shaped plastic tub... #5 plastic.

I put a layer of black airsoft bb's in the bottom, and about a half teaspoon or so of powder. I put 25 of my heavy 357 bullets in and did the shake thing.... circular for about 45 seconds or so, then up and down for about 30 seconds or so, then circular again for maybe 20 seconds. Each time I changed directions of shaking I would look through the clear lid, and never saw full adhesion.... only speckled partial coating.

Needless to say, after baking, they looked pretty crappy. The surface is mostly rough, incomplete coverage, basically crap. I even tried double coating.... same thing, just a double layer of crap, still incomplete coverage...

Long lead up to my main question.... how does powder "go bad" ? Does it get moist? What else could cause the lack of static attraction?

 

[popper]

Powder doesn't look like it flowed well. Do they pass smash test? My guess, oven temp too high as it cured the powder before flowing. I have Smokes powder stored in orig. double bag for like 3 yrs, in garage. No problem. If they pass smash and size, shoot em.

 

[hornetguy]

I haven't smashed any yet. I'm more concerned with the lack of static attraction.
I guess I could try it without the bb's.... maybe I should stop and buy some kool whip on the way home.
Does anyone know HOW powder goes bad?
Is it moisture, and if so, could I put dessicant bags in with the powder to dry it out? Obviously heating it up to dry it out would not be a big help.

All of this is mostly just speculation, trying to learn more about it. I have a couple of pounds of Smoke's powder coming, so that should eliminate the "bad powder" issue.

Does anyone have a definitive answer to whether bb's are necessary, or not? I've seen it done both ways.

 

[shuz]

I don't use bb's, but I live in a rather dry, sometimes, climate. I do not try to powder coat until the relative humidity drops below 50%. I get excellent coverage with Smokes powders that I've kept in a Kirkland nut jar with lid for a couple of years now.

 

[popper]

Yes, moisture and dust will mess with the powder. I use the ASBBs in a tupperware tub. Sometimes takes a lot of swirl/shake. I tend to use gloves or some hand insulation - plastic has a dielecric constant (insulator) that is good but your hands will bleed off some charge. If you have a powder that doesn't flow good and don't knock off excess you get clumpy results. I have trouble with black but red is fine. Size and shoot what you got if smash passes.

 

[Rockydoc]

I don’t think the bb’s are necessary , but they don’t hurt. Just more trouble to use. I use a vibratory tumbler, with or without bb’s. It takes less effort. I either pick them out with dental cotton pliers and tap them on the side of the bowl to remove excess powder or dump bullets and powder onto a wire screen to separate excess powder.
I don’t start timing the curing until the powder glazes over.

 

[Reloader762]

From reading on most of the PC mfg. websites it states that powder coat i.e. polyesters has a 1 to 3 years shelf life if stored in deal conditions. However, that doesn't mean it always goes bad in that time period.

I generally find that if you're not getting a good coat on the first try, you either have a powder that has gone bad on its own or it has been exposed to excessive heat or moisture over time. Your bullets could also be contaminated, I wash mine in acetone and dry before I coat and handle them with nitrile gloves if I have to handle them getting them into the container for coating.

Static electricity is your friend and humidity is your enemy when it comes to powder coating, here in NC it's always humid except for the coldest and driest days of winter and it's been warm and wet here all winter. Some individuals don't need them but I've always used the air soft BB's It helps generate extra static and acts as a buffer between the bullets which I think give me a better coating.

 

[Tomme boy]

Kinda looks like what Harbor Freight powders acted like. Hot flock them if you can. Don't go over about 100* if you do. Its what I used to have to do to get the HF powder to work.

 

[Snakeoil]

I don't use PC but find the discussion interesting. I know that static is a key factor in the PC adhering. Never realized that over time, it could lose the ability to hold a static charge. I would think that moisture is the primary culprit. Hence Tomme's success in cooking it a tad. I wonder if storage in a cooler with desiccant bags inside would lengthen the shelf life?

I'll but out, now. Uniformed opinions have no value.

 

[fiver]

how did you cook them?
with certain mixes i get a coating that looks like it's not gonna do anything.
you can see through it, and it looks more like fuzz than a coating.

but when i cook them i hold them around 350 for at least 10 minutes and watch them go through a 'wet' stage.
this is when everything goes from the fluff to the wet and the powder flows and links together, you can see the powder take on it's color and coverage.
then i bump and hold them at 400 for 22 minutes to cure them.

anyway, the powder itself can take in and hold moisture.
not the end of the world, water has a positive charge,,, problem is so does the bullet.
you just gotta work the static a bit more.

 

[Rick H]

I too check for the bullets to "wet out" before setting my timer for 20 minutes. They generally look pretty bad before they wet out and flow. I bake at 400 degrees. I use a Taylor oven thermometer in my Black and Decker convection oven. The settings on the dial were off as much as 75 degrees low.

 

[fiver]

yep on the low side.
i use the toaster setting.
it will climb up pretty slowly and i can flip over to the convection setting to fan the air around for about 5 minutes or so with no temp change, then back again.

 

[JWFilips]

The guys above have some good suggestions! If you think it is moisture ( I do not) I have a small container of Silica gel ...the color changing kind which I place in my shaker container when I'm not using it ! It will turn pink in about a month even in the sealed container! Also Heat you bullets up with a hair drier until the are uncomfortable to handle! I mix them around in a container while heating When just too warm to handle I dump them in my shaker container! Before I stand them up I tap the tweezers holding them a few times to knock off the excess powder! Then stand them up for baking!
If the powder is in 2 zip lock bags it is "Smokes" Seems to last for years

 

[hornetguy]

I probably should have bought a convection type oven... I just got the $20 dollar wally world one. Couldn't find my old oven, probably got tossed.
I had read that 400 is where they needed to cook, so I just set the dial on the oven to 350 and let em go... I did pre-heat the oven first.

Like I said, when I first bought this powder, it coated almost too good... I coated some 45 swc tumble lube style, and the little grooves almost disappeared, the coating was so thick. They looked really nice, just sorta rounded out... no sharp edges.

I might try some more tonight, with only the black powder.... gotta play with something until Smoke's powder arrives.

 

[hornetguy]

I'll but out, now. Uniformed opinions have no value

I disagree.... brainstorming is usually a good thing.
I really appreciate ALL the comments and advice.... surely I can get this figured out, but I was getting a bit bummed that it wasn't working for me.

 

[JWFilips]

I really appreciate ALL the comments and advice.... surely I can get this figured out, but I was getting a bit bummed that it wasn't working for me.

How much experience do you have at Powder coating? If you are just starting out well you have to make some hurdles along the way until you get proficient with it! If you are very experienced then you may have real problems to solve!

 

[hornetguy]

How much experience do you have at Powder coating? If you are just starting out well you have to make some hurdles along the way until you get proficient with it! If you are very experienced then you may have real problems to solve!

I'm just starting out, again. I tried it back when it first became a "thing", several years back. I got some HF powder and did the shake and bake. The results weren't all that great, not bad, just not great. I then bought two different colors, blue and black, from some online powder sales place. That's the stuff I'm trying to use now. I just did a few more, using the black, and had only slightly better results than with the blue that I posted pics of. This powder worked and flowed really well when I first bought it.

I'm going with the notion that this powder has gone south... When my new powder arrives, I'll try some more bullets, and I think I'll have better results.
Here's a pic of the black ones I just did. I used a different container, and still didn't get good adhesion.... it was better, but not good enough. The powder almost "feels" damp.... it sort of clumps together instead of flowing around like flour does.... it sort of sticks together sort of like baking powder, if that makes any sense.
I know I need a lot more "practice" to get the results you guys get, but I at least want to eliminate the powder as being the problem.

 

[Tomme boy]

I just got some bronze metallic powder from Prismatic. I had problems with it coating the first 2 times I tried to use it. Turns out it has a lot of clear powder in it. And man it looked like the powder was very wet in the bucket I was using to tumble them. Clumping like crazy. I baked them and they look fine.

I talked to Prismatic and they said it was the metal flakes that were heavier than the powder. FYI the metal flakes are not metal. They are not in most paints either. But that was what made the powder look like it was clumping in my case.

Just make sure that if you do try to heat the bullets up, don't heat them much over 100* or the powder will start to melt and ALL the powdr will stick to the bullets and can end up with a giant ball of sticky bullets in your container. Ask me how i know! LOL!!!

 

[Spindrift]

I've also found pre-heating the bullets to be very useful for powder adhesion.
Even if the bullets appear clean and dry, there will be some microscopic condensation on a cold metal surface.
I've wondered if powder with to much moisture could be re-activated in a microwave oven, since the microwaves only heat the water molecules. Haven't tried it yet, though.

 

[hornetguy]

Just make sure that if you do try to heat the bullets up, don't heat them much over 100* or the powder will start to melt and ALL the powdr will stick to the bullets and can end up with a giant ball of sticky bullets in your container. Ask me how i know! LOL!!!

I've wondered if powder with to much moisture could be re-activated in a microwave oven, since the microwaves only heat the water molecules. Haven't tried it yet, though.

I did preheat one batch that I did after the ones in the pic, and had them probably slightly over 100... I could handle them, but they felt almost too hot to be comfortable.... what's that, about 120 or so? They didn't seem to work any better than those 45's in the pic.

The idea of the microwave to "dry" out the powder is interesting. I wonder how microwaves interact with this type of powder.... one way to find out, I suppose.