Home Powder coating systems

1FATGMC · January 25, 2006, 10:26:54 AM

I'm interested in this as I would like to coat some of the smaller parts on my lakester. I'm not interested in how good they look, just that they will be more resistant to the salt and easier to clean than maybe a painted piece and also maybe quicker than painting.

So with that in mind is it going to matter which system I buy, HF or Eastwood. I'm thinking the HF gun and the Eastwood powder from what you guys have said.

I'll sand blast the parts with local sand. It is what they call "blow sand" and is real fine and leaves a fine white look to the part.

There is a local guy where I buy my metal that powder coats and seems reasonable, but it always seems things cost more when I pick them up than what we talked about before hand :x . I'm thinking he could nickle and dime me to death.

One last thing. How much clearance in holes do I need? If I have a 1/2 inch bolt in a 1/2 inch hole does the hole now need to be 9/16th. Smaller holes I can go in 64ths, but over 1/2 I'd have to go in 16ths.

c ya, Sum

enjenjo · January 25, 2006, 10:55:36 AM

Up to 3/8" I make the holes 1/32 bigger, over 3/8, I go 1/16 bigger. Of course I do that on all parts anyway. It makes assembly much more pleasant.

sedanman · January 25, 2006, 11:55:50 AM

I agree with Frank about the hole sizes. Powder goes on much thicker then liquid and makes the holes smaller. We never have that luxury from our customers and always plug all blind holes, threaded holes and open holes to hold down complaints. There are different powders for specific applications and uses other then appearance. Epoxy powders have great chemical and salt resistance but chalk or dull out in UV light (sunlight). Polyesters and urethanes are best for parts that will see the sunlight but does not have the chemical resistance of epoxy. The best of both worlds are the hybrids. They are combination of both. Please remember that the thermal cure of powder is the most important factor. Unlike air dry paint, if it is not fully cured it will never cure on its own. It will chip and peel and you will not be happy. I have seen this situation give powder a bad name because the user did not understand how to check for full cure. Hope this helps.

Bruce Dorsi · January 25, 2006, 12:55:33 PM

THANK YOU for sharing your expertise! .....Of course, that leads to more questions.

Quote from: "sedanman"Epoxy powders have great chemical and salt resistance but chalk or dull out in UV light (sunlight). Polyesters and urethanes are best for parts that will see the sunlight but does not have the chemical resistance of epoxy. The best of both worlds are the hybrids. They are combination of both.

Does the exposure of the epoxy to UV light cause it to degrade, or is it simply an appearance issue?

Quote from: "sedanman"Please remember that the thermal cure of powder is the most important factor. Unlike air dry paint, if it is not fully cured it will never cure on its own. It will chip and peel and you will not be happy. I have seen this situation give powder a bad name because the user did not understand how to check for full cure.

Will you please elaborate on the cure process and how to check for full cure?

Is the cure process the same for the various types of powders?

Two more questions, and then I'll duck:

Does the silica deposited on the metal from sandblasting or glassbeading inhibit the powder from adhering well? ....Should the parts be washed with solvent to remove the silica before powder application?

Thank you for your patience! :oops:

sedanman · January 25, 2006, 03:40:41 PM

Thats fine, finaly you guys have started a subject I can help with. I have been in the coating Industry for 31 years. Now for some answers:

Powder cures by time and temperature. Most powder will come with a tech data sheet that will spell out the temp and time for you. What some don't understand is PMT. this means Peak metal temperature. NOT oven temperature.

Example: If the powder call fr 375 F for 10 minutes most think that they can heat the oven up to 375, put the part in for 10 minutes and it will cure. This will not work in most cases. PMT means the mass of metal must reach 375 F and then be held at that temp for 10 minutes. The thicker the part the longer it will take to acheive this. Powder has built in cross linker that requires this time and temp to kick over.

You can buy a small hand held digital thermometer with a remote probe fairly cheap. Attach the probe to the part that you want to cure and do a test run with out powder on it. Time how long it takes to reach PMT.

Now you are ready to powder coat the peice and bake. Remember that if you put more then one part in the oven that will change the time required to hit PMT. If they are real small parts this may not matter, such as door handles. If we are talking A frames or Brake drums, it will matter.

Checking for cure: After the parts have completely cooled off you will need a Q-tip and some Acetone. Wet the Q-tip with acetone and rub the part in a no show area 25 double rubs. You should not see any more tha en a slight spot on the Q-tip and the powder should not soften. If it does it is not cured.

As for the sand blast. I powder coated every Desiel engine in all Ford trucks from 1996 to 2003, and they were all sand blasted prior to coating.

I would just make sure that any loose sand has been removed by air blast.

DO NOT touch the fresh blasted surface with your bare hands. It will absorb the natural oil from you hands and the powder will fail there first.

Hope this helped

Sedanman

MrMopar64 · January 25, 2006, 04:33:17 PM

Quote from: "sedanman"Checking for cure: After the parts have completely cooled off you will need a Q-tip and some Acetone. Wet the Q-tip with acetone and rub the part in a no show area 25 double rubs. You should not see any more tha en a slight spot on the Q-tip and the powder should not soften. If it does it is not cured.

One more question.......
If it turns out the powder has not cured can you put it back in the oven or do you have to strip it and start over?

Thanks
MM64

1FATGMC · January 25, 2006, 08:12:20 PM

Great info. Thanks

.

For the small parts that I want to coat on the lakester it isn't like they are going to be in salt water. It is just that salt gets on things there and I need to clean the car good when I get home. I've had others there tell me the salt will come off the powder coated pieces easier.

So will just the regular powders work for what I'm trying to do?

Also I don't want to coat any pieces that I think will need changes to as I feel it would be easier for me to grind paint down and weld and/or cut whatever needs changing. So the frame and other major parts I don't want to coat as I'm sure there will be changes to the car as I go along.

Parts like these are what I'm talking about. What about the bushings I have in some of those parts? Can they be pluged and/or taped?

Thanks again,

Sum

sedanman · January 26, 2006, 07:46:02 AM

Quote from: "MrMopar64"
Quote from: "sedanman"Checking for cure: After the parts have completely cooled off you will need a Q-tip and some Acetone. Wet the Q-tip with acetone and rub the part in a no show area 25 double rubs. You should not see any more tha en a slight spot on the Q-tip and the powder should not soften. If it does it is not cured.

One more question.......
If it turns out the powder has not cured can you put it back in the oven or do you have to strip it and start over?

Thanks
MM64

Yes... It can be rebaked. As a matter fact most powder can withstand and over bake of twice the recomended time at PMT. If recoating though the powder should be sanded first to knock off the gloss and provide a profile for the second coat to adhere to. Use at least 220 grit.

Vic....

sedanman · January 26, 2006, 07:59:51 AM

Quote from: "1FATGMC"Great info. Thanks .

For the small parts that I want to coat on the lakester it isn't like they are going to be in salt water. It is just that salt gets on things there and I need to clean the car good when I get home. I've had others there tell me the salt will come off the powder coated pieces easier.

So will just the regular powders work for what I'm trying to do?

Also I don't want to coat any pieces that I think will need changes to as I feel it would be easier for me to grind paint down and weld and/or cut whatever needs changing. So the frame and other major parts I don't want to coat as I'm sure there will be changes to the car as I go along.

Parts like these are what I'm talking about. What about the bushings I have in some of those parts? Can they be pluged and/or taped?

Thanks again,

Sum

I would use epoxy on the parts you have shown. Go to your local hardware and try to locate some rubber stoppers to plug all those holes with. I would disassemble the second peice down and coat it in peices. I think I see threaded rod in a couple of those peices. Don't powder coat those if you want them to ever function again. Use zinc or nickle plated rod. I would remove the bushings if you can, if not plug them. Laboratory stoppers for test tubes come in many sizes and are heat resistant and can be cleaned off and used over and over. If you can't find those cork can be used, but they are a one time use and will fall apart upon removal.

Lab supply houses carry the stoppers. You are correct about not coating peices that will require further fabrication. Powder is harder to grind off and is plastic, so it melts when you try to weld close to it.

Vic...

nocentsracing · January 29, 2006, 12:29:15 PM

I bought a kit and some powders from Caswell Plating, out of New York, but have not used them yet. Has anyone had experience with the Caswell powders? Here's a link if anyone's interested. If memory serves me, the powder prices are much better than Eastwoods. Thanks.

http://www.caswellplating.com/

sedanman · January 30, 2006, 06:23:20 PM

Quote from: "nocentsracing"I bought a kit and some powders from Caswell Plating, out of New York, but have not used them yet. Has anyone had experience with the Caswell powders? Here's a link if anyone's interested. If memory serves me, the powder prices are much better than Eastwoods. Thanks.

http://www.caswellplating.com/

I checked out the kit.The only thing I question is the 17KV. We charge our powder 70 to 100kv. But we are high production facility and we are dependant upon first pass transfer efficiency.

Vic...