Powder coating at home!!!!

For a first-timer, experiment with some 'extra' parts until you get the hang of it. But it's pretty hard to screw up... LOL.

I'll repeat what I said about cast parts, particularly anything aluminum; make sure you 'pre-bake' the part to make sure any corrosion and/or contaminants are out of the metal. Anything less than clean dry metal will give you flaws in the coating.

 

That's what I was wondering. I have a blast cabinet that I will use a lot. My next media purchase can be determined by what you guys say. How far will a lb of material go?

 

Well................ Just gotta be prepared for the first timers flash/flamethrower. Once that's over with, it's you learn quickly the do's and dont's. Just like anything else- learn as you go, but, in this case- hopefully it's a one time lesson.

 

Just for starters- get 5lbs. Then- see how your media reacts to different metals. It's a trial and error thing, but once you know what's what, easy breezy.

 

I use aluminum oxide, can't say what grit but it's fairly fine (80 grit I think). Leaves a no-shine satin finish. I've had zero chipping issues with this finish.

As far as how much powder you use, I coated most of a motorcycle (everything except the frame, rear fender, tank, spoke wheels, and engine cases/cylinders) with about a pound. This included the swingarm, fork lowers, brake calipers/master cylinders, triple trees, handlebars, controls, rocker covers, engine side covers, oil tank, battery tray/cover, and all misc brackets and covers. Five pounds would coat every possible part on a car you could do at home with some left over.

Don't try to recycle the overspray, and put plenty of plastic down to catch it. You DON'T want to be vacuuming this stuff up, it will explode your vacuum!

 

On small parts I use a toaster oven.

 

I started with a cheap gun ... and a good commerical oven for doing my own stuff.... but it has now turned into a business out of my garage that is fairly successful.... to the point where I am turning away work. I buy all my powder from www.columbiacoatings.com and prismatic. I specialize in bicycles, motorcycles, wheels, and hot rod parts. You can do some really cools things with dormants, chameleons, translucents, and Metallics that are really hard to do with paint.

www.powdercoatman.com

 

Thanks for the info guys. This is shoring up my decision to go forward.

The good thing is, that when I built my shop, I drove 2, 6' copper ground rods in the ground before I poured the slab. They are sticking up about and inch. Should help with the grounding on the gun.

 

very interesting info guys, thanx to all who shared. Lucky to have a couple of friends in the business!

 

So what about ceramic coatings? Different animal all together?

 

I was going to do some of my own powder coating for my RPU but with the limited amount of space in my little 2 car garage along with the work and cost involved with trying to set up an oven etc., I just decided to have a powder coating shop do my stuff.
On top of that the number of parts I am having done was relatively low.
Best decision for me, drop the parts off and pick up nicely coated parts.

 

I just think it would be cool to blast a part, coat it and put it away. Then it would be ready when I am. I have the space, although the shop usually looks like a tool grenade went off.

 

Regarding the advice to preheat parts at up 400* for up to an hour, would make me concerned about changes that could effect to the temper of the metal. I was trained those temps will change the temper, and will destroy certain parts. Do you see any discoloring of bare metal when you do this? Aluminum is tempered at far lower temps than steel.

 

If you had an understanding of basic metallurgy you would understand that 400 degrees is well below most metals lower critical temperature and at that low temperature no changes to the material will take place.

This is true with steel parts however with certain aluminum alloys powder coating will soften (anneal) them.
This is a basic iron carbon diagram and the link that explains it.





http://www.substech.com/dokuwiki/doku.php?id=iron-carbon_phase_diagram

 

No discoloring has ever appeared. And keep in mind that this is the heat needed to cure the powder in any case (you can cure at a lower heat, but the coating won't be as durable or always give you the same surface finish). Yes, there are some items that won't take that temp; any kind of spring. They recommend holding cure heat down to 325-350 degrees, although that may not always be low enough on smaller springs. I'd recommended painting springs, just to be safe. You don't want to media-blast most springs either, as that will also remove the temper.

Aluminum and castings are generally the items that need the pre-bake; castings as they can be porous, although anything that has/had heavy rust should probably be pre-baked too. I'll pre-bake any aluminum part that has pitting, cast or not. The slightest amount of any contaminant left in/on the metal will 'pop' when exposed to cure heat and ruin your finish. Powder is much more sensitive to this compared to paint. Aluminum castings are the worst; ANY aluminum casting that contained fluids/lubricants or has pitting corrosion will get solvent cleaned, then blasted, then pre-baked, then blasted again. If you find any visible white 'dots' on a aluminum casting after the pre-bake, you didn't get all the corrosion; I've had a few that took up to three 'bake/blast' cycles before they came up clean.

 

Sorry Larry, that's a nice chart and I don't question it's accuracy, but I think your misapplying it here. Metallurgical changes to occur at far lower temperatures than shown here.

Here's a chart showing discoloration starting to occur at 420*f, which does effect hardness. http://www.anvilfire.com/article.php?bodyName=/FAQs/temper_colors_hardness.htm

Here's an article on failure ****ysis of steel parts, see the section on Intergranular Brittle Fracture showing embrittlement can start at 450*f.
http://www.asminternational.org/do***ents/10192/1849770/05113G_Chapter2.pdf

I can search further for more info, but this all backs up my training as a mechanic, to keep heating of bearings below 350*. I saw a lot of bearings damaged in the field by somebody getting a little too carried away heating them up. Just how accurate is that oven your using to heat your parts? We used temp sticks back then to check the temp (predated cheep infrared guns). The sticks would melt at a certain temperature, and we could monitor the temperature of the parts as they baked, pulling them out when the got to 350*.

Or out in the field it was when they could sizzle spit

 

And for aluminum, the temp range for structural changes in the metal start far lower than that.

 

There is no point in debating this any further. For the vast majority of parts that guys will powder coat we are talking about plain low carbon steel.

No significant metallurgical changes will take place below that lower critical temperature. ( changes in metallurgical structure from the heating and cooling cycles involved in powder coating)

That metal color chart is also what we use as a means of indicating the color ranges steel go through when heated.

There is a "blue brittle" range at 650F where steel fractures easily at that temperature when bent, but that still doesn't lead to any metallurgical changes when the material cools.

Yes, bearings and the like can change when heated too much but then you are talking about high carbon steels.

Metallurgy is a fascinating subject, some of our students love it, others are just confused all to hell on it

 

Which I mentioned previously.

 

So, what would a guy do with an aluminum intake?

 

Thanks for clarifying that Larry, that helps a lot.

 

I had an old Edelbrock 573 tri power Y Block intake done for my RPU.
I repaired the damaged parts and then he heated it up a little to get out any impurities.
Then he coated it with Eastwood cast aluminum look powder followed by a satin clear.
It turned out very nice.

 

I have the Cadillac Weiand 2x4 I just got. Trying to figure out how to make it look nice with minimal maintenance. Any pics?

 

Here you go.

 

Dang, I like that.

 

So do you paint like painting a car? Overlap etc.

 

We Have had the eastwood/home oven setup in the shop and farm out the bigger stuff for many years now.
Basically anybody can turn out acceptable parts right off but the discerning eye will note that it is often too thick in the open areas too thin in the crevices and not as durable.

Someone who cares to pay attention to the details of prep, good grounding of parts, temp etc. and adjusts for different parts/conditions can with practice achieve an exceptional thin even coating that is very durable. the biggest difference in quality seems to be in the powders and operators not the equipment.

It's not really like painting as the gun puts out a fog in the general area and a portion is attracted to the part. this is why good grounding of the part is so important and why like chrome crevices are the most difficult to cover.

 

Oh and dry weather is best.
A good day for static electricity is a good day for powdercoating.

 

Average humidity around here is 45-50%

 

Nice, you will be wasting a lot less powder than we do up here in the great lakes at 65-85%