View Full Version : powder coat prep work?

02-19-2010, 12:56 PM
I sand basted my parts.What else should I do before powder coating.I thought I read I should rinse with acetone?Is there any specific procedure I should do?Also will standard powder coat(up to 400F) work on calipers or do I need high temp?

02-19-2010, 01:22 PM
I have not powder coated automotive parts but used to have industrial parts powder coated. Basically at this point your goal should be to wash the parts to remove any oil or dirt residue... just like you would with spray painting. Hopefully you degreased the parts before sandblasting so you didn't drive the debris into the surface. Regardless, Acetone or any other prep solvent you would normally use prior to spray painting will work.

As for calipers, they do get hot, but 400oF is pretty far up there. The wet boiling point for "new" fluid may be above that, but once the fluid has been in use for a while the boiling point is lower. If you manage to get the brake caliper up over 400oF, you probably have more to worry about than damaged paint.

02-19-2010, 08:43 PM
I use the metal prep Metal Wash (https://www.eastwood.com/eastwood-s-metal-wash.html) that I bought with the powder, from Eastwood. You mix with water and spray on. Always wear gloves - this stuff is a mild acid. Never touch a prepaired surface with your fingers. The oils on you skin will prevent proper adhesion of the powder.

02-19-2010, 09:36 PM
I agree. I also tack rag the pieces just before hanging them to coat.

02-20-2010, 03:30 PM
I agree with not every touching parts with bare hands. I wear disposible rubber gloves the entire time I am handling parts during and after sandblasting. I also preheat parts and then let them cool before powdercoating, especially on cast parts. More than once I thought a part was blasted clean only to have oil or greese seep out from somewhere when I heated it up.

02-20-2010, 05:51 PM
I did not have any blasting equipment available to me
so I improvised. I stripped each piece with a paint gel
strip compound and wire brushes. Washed the part in paint
thinner. Next I soaked them 24 hours minimum in a liquid
degreaser. Soap and water final cleaning and then preheat
to dry. A final wash with fast drying acetone and then spray
the powder.

As mentioned, never touch the final cleaned piece with fingers.
Mine might not be quite correct procedure but it worked for me.
I worked with the chemicals in a well ventilated space.



02-20-2010, 11:07 PM
I degrease in kerosene for grease removal. Sand blast in a blast cabinet (my parts were very rusty), wash with Metal Wash (Eastwood product, rust inhibitor and degreaser), and then bake at 400 for 30 minutes to dry. I always preheat at 400F before powder coating. There is nothing better than powercoating a hot part. It sticks better and you can remove ground clip and stick gun up close in corners and add powder where it doesn't want to flow otherwise.

The 50 year old parts look like new and are bulletproof.







02-21-2010, 08:19 AM
Nice pictures, Pat - hope your wife wasn't around when you snuck those springs into the kitchen oven!

02-21-2010, 09:32 AM
Wow, my powder coat oven isn't that clean.

I usually wire parts to be coated to the oven rack and slip the rack into a coating box (old dishwasher box) that has an internal wooden frame to hold the racks. I cut an opening on the top of the box for a flourescent light and clip the ground to the rack. I lined the bottom of the box with 6mil plastic sheet to reclaim powder. The box keeps the excess powder contained. Also, I always wear a 3M particle mask while coating. Remember, if you can smell it, you're inhaling it too.

Then it's just a matter of carefully sliding the rack with coated parts into the pre-heated oven. 400 for 20min. I put an electronic timer in my pocket so I can leave the shop while the powder cures - fumes are toxic, so I've read.

The reason to preheat cast parts is to bake out the moisture so it doesn't foul the coating during curing.

02-21-2010, 09:38 AM
Nice work Pat!

02-21-2010, 11:40 AM
Peter - any chance you can post a photo of the dishwasher set up? Thanks

02-21-2010, 01:29 PM
Sure. I'll snap one for you this afternoon. It IS just a box but I built an internal wooden framework for it.

02-21-2010, 01:48 PM
I bought an almost new digitally-controlled oven on Craigs list for $50 and built some storage cabinets and installed wall-mounted oven. Had to extend 220V to it, though (note, ovens require 22V with neutral and ground, because some circuits are 110V). Many 220V circuits don't have neutral.

Those coil springs were done with Eastwood Argent Silver and satin clear coat. That was my first try with clear coat and they came out beautifully. I'm still a neophyte powder coater but honestly, parts look like they are professionally done.

My wife didn't mind except she was jealous as the oven was cleaner and nicer than the one that came with our house. Given how she can barely walk thru the garage, I think the oven is the least of my worries.



02-21-2010, 03:16 PM
my PC booth

02-21-2010, 03:17 PM
and curing oven

02-21-2010, 04:45 PM
Very nice Peter

If this will keep powder off my kids snowboards and bikes, my wife will be slightly happier with me (that's an incremental move in the right direction).

Do you have a favored powdercoat supplies suppler? I use Eastwood but am always looking for other options.

02-21-2010, 06:01 PM
Gosh, <span style="font-style: italic">it's good to be an American</span>...

Thanks for posting Peter. I thought you meant you were <span style="text-decoration: underline"><span style="font-style: italic">using</span></span> a dishwasher "box", (i.e. plastic interior).
I think I'll look for a D.O.A. dishwasher, (they're abundant), pull the door, guts and motor. I think I can put the oven and a powder coat spray booth side by side, at a good working height, in my shop.

02-21-2010, 07:52 PM
Gosh, <span style="font-style: italic">it's good to be an American</span>...


02-21-2010, 08:57 PM
...<span style="font-style: italic">resourceful</span>, Frank.

In fact, I'll have to look at a few of those cases and see if there are any with a continuous lip, so as to join 2 cases face to face. Could be the basis for a blast cabinet. hmmm...

02-22-2010, 06:42 AM

02-22-2010, 06:49 AM
another home brew idea here

https://www.ford-trucks.com/article/idx/7...ng_Cabinet.html (https://www.ford-trucks.com/article/idx/73/007/Garage_Tools__Accessories/article/Build_Your_Own_Grit_Blasting_Cabinet.html)

02-22-2010, 09:04 AM
thanks Frank! I should be able to come up with something. Great website. I bookmarked it.

02-22-2010, 02:18 PM
I buy some Eastwood specialty powders but for basic blacks (in various gloss %), I but bulk through ebay 5lbs at a time. Eastwood's black wrinkle comes out really nice, not too grainy and EASY. Haven't tried clear coating but I've had some on my shelf for years.

My powder gun is the original Eastwood home gun from when they first started making them. I heard the HF gun is more than adequate and inexpensive.

As far as the diswasher box, it's a perfect size for most items, the inside of a dishwasher (plastic or s.s.) would be OK too but too small for a lot of items.

I built a small lazy-susan for painting small items as well as a hanging hook on a swivel.

I'd really like a nice big oven. I read somewhere online where a guy extended his oven with aluminum faced ductwork insulation. Probably OK for 20 minutes at a time without burning the joint down.