My first ever powdercoat

[muddyfox]

Alright peeps, I need some guidance from all y'all powdercoaters out there.

So I put together this cheap powdercoating setup and I'm powdercoating in a highly inappropriate space but it's the best I can do given my living arrangements.

My process is:
- dry sand @220 grit
- clean with acetone wearing nitrile gloves
- put in cold small toaster oven (forgot to preheat) and use IR temperature meter to read the pedal surface temperature
- once the part has reached 200C (~400F) as measured by the meter, set timer to 15 minutes (the powder actually started to liquify at around 120C (~250F) and it took several minutes to reach 200C)
- when done, remove from oven and let cool down

Here's my first ever shot at it. Questions after the pics (taken with a cellphone camera with focus issues).

1.

2.

3.

4.

5.

6.

7.


In order of appearance:

Pic1. I did get a nice uniform gloss. Very happy with that one but the color is slightly darker than the powder itself. Is this normal and color-dependent?

Pic2. There's a lip forming at the bottom edge of the box. I assume this is from too much powder?

Pic3/4/5. There's a black line along all the edges. Powder seems to have pooled on the edge but not over it. How do I get uniform coverage? It looked fine when powdered, the coat separated some time during the curing process. I don't think it was lack of powder because in Pic4 you can clearly see that even the inside of the cover is amply covered with powder, not to mention that lip of excess powder (I'm guessing here). Why is the powder not sticking to the bottom edge when the top edges (Pic1) are covered just fine? Is it because the edges are sharper? Should I round the bottom edges some?

Pic6. there's also some powder pitting where there was no aluminum pitting. I checked the edges prior to coating and they were fine. Same problem as with 3/4/5?

Pic7. Again with the edges showing, now on the screw holes. Also, one major pit near the hole and one smaller. What could have caused that one?

All things considered, this turned out way better than I hoped. The enclosure is completely usable, I'm just nitpicking here. If possible I'd like to iron out these tiny imperfections and I'll be set to finally box some circuits. I can't believe how easy this actually is, even when conditions are far from ideal. 

Thoughts?

[Leevibe]

I can't answer your questions but that looks very good! I've never achieved results that good and that was your first one. Nice! What gun are you using?

[muddyfox]

I'm using this one here.

http://nordicpulver.dk/index.php?route=product/product&product_id=51

It's a tribo gun, not a corona. I'm given to understand it's the same technology Electrostaticmagic gun uses (no high voltage). That's not the reason I bought it, I bought it because it was by far the cheapest option shipped to my door.
For whom it may concern, the seller lives in Denmark, is very forthcoming and gave me a really good deal (just shipping from ESM almost surpassed the price of the entire gun from this guy). I was having some financial troubles putting the entire setup together and the guy kept checking in with me how the process was going and even shared some tips on ovens and air compressors and watertraps and fire hazard and such. I can highly recommend him.

Like I said, I'm really splitting hairs here. If this came in the mail from any of the powdercoaters, I'd be perfectly content with it. As it stands, I'd just like to iron out the wrinkles in the process if at all possible.
Right now I'm thinking (as there's nothing I can do about air contamination, I'm coating in my apartment building basement storage unit)
- way less powder
- take a dremel to the sharp edges and take the edge off

[wgc]

That looks great for first shot!

Hard to guage color, opacity, and gloss via raw powder. They all influence final perception of color, and all change during the cure.

I think the bead and thin edges are from too much time in a ramping oven. So your powder is in the fluid state too long.

You probably don't need to sand, just degrease.

Preheat your oven, and bake your part before shooting powder, letting it cool first before shooting. This gets any moisture out of the metal pores.

Practice!  Do a test piece or three with desired powder before shooting your box.

[rullywowr]

Hi Muddy!

Welcome to the fun world of powder coating!  You did a great job for your first powdercoat.  You are on the right track.

Looks like you did use a little too much powder.  Too much and it will run just like if you were painting.  The powder that I use cures at 385F.  The infrared temp gun is cool  but once you figure out what your oven is running at you can just set it there and forget it.  Once the powder starts to "flow" or becomes liquid, then you can set your timer (or the oven) for 15 minutes.

Are you elevating your enclosure off the pan?  You need to make sure the enclosure is floating somehow.  If the bottom edges are sitting on the pan, the enclosure will stick and pool to the pan.  I made a jig with screws and metal plates which raises the enclosure off the oven pan surface.



If you try and take that lip off with a dremel or sharp knife, you will mar the surface and it won't look like the rest of the enclosure.  The really only good way to do it would be to strip it all down and start over.  Either some good chemical stripper or a sandblaster will work for this.

Your process is pretty sound.  Here is my process.

- Drill holes first if possible, this ensures you won't mar up the finish after powder coating during drilling.
- Wipe the entire enclosure down with acetone and a lint-free rag.  Keep doing this until no more "black stuff" comes off the enclosure.  I don't sand at all, no need really.
- Pre Bake the enclosure at the same temp you are curing at (385F) for 15 minutes.  This allows any trapped gasses in the enclosure to escape.  Let cool completely
- Ground your enclosures and apply powder.  You want enough on there to ensure good coverage but not so much it runs.  If you are worried about it you can go a little bit on the lighter side
- Carefully put your enclosure in the oven.  Again, the metal plate rig with screws helps with this part.
- (optional) After the powder starts to flow you can wait about 5 minutes, remove the part and hit it again with the powder while it is still hot.  This is called "hot flocking" and can work sometimes.  It is best if you don't need to do this but sometimes its really hard to get uniform coverage if you don't.  The sticky powder will attract the new powder and grounding the enclosure is useful but not really necessary.  Hot flocking clear especially over chrome usually doesn't work favorably
- Bake for 15 minutes and let cool in the oven completely.

A better gun will ensure better adhesion, however I have heard that the best thing to do to improve your powder gun setup is to ensure you have a great ground.  Most of the forums online say to do this, you can install a grounding rod in the earth which your powder coating rig is attached to.  I haven't done this yet but heard it really increases powder adhesion. 

A little practice and you will be popping out nice enclosures with a lot less hassle than spray painting. 

[muddyfox]

I think the bead and thin edges are from too much time in a ramping oven. So your powder is in the fluid state too long.
Preheat your oven, and bake your part before shooting powder, letting it cool first before shooting. This gets any moisture out of the metal pores.

First of all, thanks for chiming in guys!

Skinning the cat all over again, I see. 

The guy I bought the powder from told me to put it in a cold oven. Seeing the actual bead, it being liquified for too long makes perfect sense.
And the moisture in the metal pores (seeing how I didn't sand it much) makes sense as well, probably that's where the pitting came from.

More practice is in order, I need to find some scrap metal. Testing on actual boxes is prohibitively expensive although like I said, it's a perfectly usable enclosure with nice gloss to it. No orange peel whatsoever.

[muddyfox]

Hi Muddy!

Welcome to the fun world of powder coating!  You did a great job for your first powdercoat.  You are on the right track.

Looks like you did use a little too much powder.  Too much and it will run just like if you were painting.  The powder that I use cures at 385F.  The infrared temp gun is cool  but once you figure out what your oven is running at you can just set it there and forget it.  Once the powder starts to "flow" or becomes liquid, then you can set your timer (or the oven) for 15 minutes.

Yeah, I went in all guns blazing! 
My storage unit has really crappy lighting and I couldn't quite make out if I missed a spot or two so I guess I piled it on too thick thinking it'd be a safe bet. Obviously I could have done with much less.
Now, I may be wrong about this but this is what I understood from what I read on various forums... liquid powdercoat is no indication that the curing process has started. The actual part needs to be up to the curing temperature of the powder (200C in my case) and only then does the proper bonding happen. It seems to be a problem with car parts coating, where there's significant difference in material thickness and thin parts can overbake while thicker haven't completely cured. In my case, powder started liquifying at 120C already and it was in liquid state for a good 5 minutes until the actual box got up to 200C. Nice heatsink, aluminum is.    I don't know if there's anything to this but I've read it more than once...
So I'm guessing less overall curing time is needed and/or I need to preheat the oven to minimize the time spent in a liquid state (flash heat it, so to speak instead of a gradual ramp).

Are you elevating your enclosure off the pan?  You need to make sure the enclosure is floating somehow.  If the bottom edges are sitting on the pan, the enclosure will stick and pool to the pan.  I made a jig with screws and metal plates which raises the enclosure off the oven pan surface.



If you try and take that lip off with a dremel or sharp knife, you will mar the surface and it won't look like the rest of the enclosure.  The really only good way to do it would be to strip it all down and start over.  Either some good chemical stripper or a sandblaster will work for this.

I have a contraption very similar to yours (I'd take a picture but it's in the oven down in storage now), screws holding the object up. You can even see the four screwmarks on the box lid 
Although I'm satisfied with this box, I'm gonna try stripping it just to see how that goes. Stevie told me to leave it overnight in a bucket of acetone, can't hurt trying. Sandblasting is not an option and I don't even want to think about handsanding all this off. 

Now, about your contraption... How do you get it to stay white and have a green part on top? When I sprayed it, the entire metal structure got yellow and is now nicely baked as well. 

Your process is pretty sound.  Here is my process.

- Drill holes first if possible, this ensures you won't mar up the finish after powder coating during drilling.
- Wipe the entire enclosure down with acetone and a lint-free rag.  Keep doing this until no more "black stuff" comes off the enclosure.  I don't sand at all, no need really.
- Pre Bake the enclosure at the same temp you are curing at (385F) for 15 minutes.  This allows any trapped gasses in the enclosure to escape.  Let cool completely
- Ground your enclosures and apply powder.  You want enough on there to ensure good coverage but not so much it runs.  If you are worried about it you can go a little bit on the lighter side
- Carefully put your enclosure in the oven.  Again, the metal plate rig with screws helps with this part.
- (optional) After the powder starts to flow you can wait about 5 minutes, remove the part and hit it again with the powder while it is still hot.  This is called "hot flocking" and can work sometimes.  It is best if you don't need to do this but sometimes its really hard to get uniform coverage if you don't.  The sticky powder will attract the new powder and grounding the enclosure is useful but not really necessary.  Hot flocking clear especially over chrome usually doesn't work favorably
- Bake for 15 minutes and let cool in the oven completely.

Yeah, your process is almost the same as mine. A few points, though...
- when you hotflock 5 minutes after it started to flow, do you bake for additional 15 minutes making it a total of 20? Do you normally bake for 20? i see your temperature is somewhat lower than mine but the guy I bought the powder from told me to bake it at 200 for 15-20 minutes. He unfortunately didn't specify whether that's 15-20 after the part got up to 200, or whether it's cold or preheated oven. Which, you'll agree, makes a world of difference. 
Also, do you just turn off the oven and let it cool or do you open the door to speed up the cooling?

So right now, I'm thinking
-clean with acetone
-prebake at 200, let cool
-preheat oven, spray box while waiting
-put in oven, wait till liquid
-15 minutes, take out

A better gun will ensure better adhesion, however I have heard that the best thing to do to improve your powder gun setup is to ensure you have a great ground.  Most of the forums online say to do this, you can install a grounding rod in the earth which your powder coating rig is attached to.  I haven't done this yet but heard it really increases powder adhesion. 

This makes sense for a corona gun where you actually have ground potential and an electric field that charges the powder. From what I gather, tribo works without electricity because the powder gets charged by friction while travelling through a ptfe plastic tube that ionizes it. The only "ground" potential is the one connecting the metal body of the gun and the metal of the object being coated. That's my understanding anyways, that and a dollar will hopefully get you a cup of coffee... 

[Clayford]

[rullywowr]

Now, about your contraption... How do you get it to stay white and have a green part on top? When I sprayed it, the entire metal structure got yellow and is now nicely baked as well. 

Haha.  I just threw that neon green one up there as an example.  The last one I baked was white.  There are layers upon layers of different coatings under there.  I just sand the tops of the screws from time to time to ensure a good ground.

[muddyfox]

LOL Clay!  Never seen that gif before...

So, situation update... just came back from my storage unit where I coated my second box, again a 1590A, same yellow powder.

Much better! I used way less powder (maybe could have used a smidgen more) and there's no pooling to be seen anywhere. I also preheated the box until the oven reached 200C (I'm guessing the box was at 150Cish when I took it out), left it to cool and than sprayed it. When I put it back in the oven, the oven was down to roughly 100C or so. No pooling and nice edge coverage.

More dust this time, though. It looks fine when powdered, imperfections come out when cured. They are tiny protrusions and I'm pretty sure it's dust. Nothing I can do about it, it's a storage unit, not a pro shop.  That said, even the boxes I got from Banzai had some bumps to them so I may not be doing all that badly!  It's gonna get covered with a decal and a coat of envirotex eventually anyways so I'm just being too sensitive.

Will try white tomorrow!

[Clayford]

Oh wow... Thats from an OLD Apple ad. THe guy is all grown up and when he found out it's a popular gif, he remade a current one of himself. Regardless... My point is - well done!

[rullywowr]

Nicely done!  You may want to try hooking up a shop vac near where you are spraying to suck up any excess powder and dust in the air. 

[wgc]

There's really just a few key things and then its all practice

For me the key things are, not necessarily in order

Good ground
Clean parts, degreased
Prebake parts
amount of powder
Cure schedule, with attention to ramp time
Properly stored powder

[muddyfox]

Cure schedule, with attention to ramp time

Is it ok (since the oven is still somewhat hot from the prebaking) to just keep the oven on and put freshly powdered pedal in there (so basically no ramp time, straight to the max heat)? Would it help or make things worse?

[muddyfox]

Nicely done!  You may want to try hooking up a shop vac near where you are spraying to suck up any excess powder and dust in the air.

It's just a tiny storage cubicle (already jam packed with crap), really no space for a shop vac. I also got some grief from the neighbors yesterday because I ran my tiny air compressor at 9PM for three minutes just to store enough air for one pedal. A vac that's constantly on would get me banned from the storage unit so I'll just need to live with the dust. I have a decent mask and really there isn't all that much excess powder (except when cleaning up  ). Another point is that a vac would likely stir up the air in the storage unit, making it even more difficult to get a dust-free coat...
Also I'm told that vacs could possibly pose a fire hazard with plastic dust. I'm sure there's not nearly enough with my spraying volume for that to happen but since it's an underground storage unit with virtually no ventilation, I'd rather play it as safe as possible.