Powder Coating Discussion - Answers from a guy that does it for a living

[kadams]

Well, here is my effort to give back to the IH Cub Cadet community. While I lack expertise in IH Cub Cadets, as the owner and operator of a small custom coating business, and after many years of studying and talking with other coaters, I do know a lot about powder coating, and I would be glad to share my knowledge with all of you. I don't want your money, but I do want anyone interested in powder coating their own parts, or having coating done for them to end up with good quality work. If it weren't for this forum, I'd probably be stuck riding around on a mid 90's Wally World MTD, instead of my glorious little 147. Besides, there is so much misinformation out there, it behooves me, as it does everyone in the industry, to try to set the facts straight.

So, without further adieu, let me just say that I am here to dispel myths, set facts straight, offer guidance, and maybe even help you folks with the occasional colour match. Let's get the ball rolling. Ready? GO!

 

[dtanner]

I would love to have some correct info on power coating.Just how many $$$ would it cost to use powercoat instead of paint

 

[kweaver]

Curing Oven

Dennis this is for you ...
If you don't use one that much or have room for a oven in your shop then why not build a temporary one on your patio or any place you have a slab of concrete. Just get a load of concrete blocks and dry stack them and build a roof that can withstand the heat and go for it.

When I was making the Pin Tools I just dry stacked firebrick on the floor and put an oven burner in there and used a probe to check the temp.

 

[kadams]

Don T, That sort of depends on the part(s) you are considering coating or painting. Generally speaking, if you are paying a shop to do the work, a powder coat finish is cheaper than paint.

Of course, there are geographical considerations, the actual colour and chemistry of the power and paint can have an impact, and so on. Actual prep work of the substrate is much the same, so has little influence on the final cost of a job.

Of course, all of this is moot if you are wanting to compare the cost of rattle cans versus powder coating at home. What are your plans?

 

[dross]

Keith, What happens when you mix 2 colors. I know they are granulated does the end result end up speckled or does it blend at all?

 

[kadams]

Dave, oddly enough, it seems to depend on formulation. I have personally mixed a few different polyesters together, and some of them blend in to a new colour, while others simple come out speckled. I believe that the deciding factor has something to do with the waxes that are used in production, but hey, that's for the guys in the white coats to decide.

For anyone spraying the end product, you really just have to try mixing a little to spray and cure. Just keep it within the family when you mix things, or the results will not be pleasing. Mixing two polyesters is okay, but mixing a polyester and an epoxy won't work at all.

Now, if you're asking because you're hoping to match a colour by formulating it yourself from two or more different ones, I can tell you that there are a lot of colours out there ready made. My main supplier currently offers more than 6,500 colours.

 

[kweaver]

Don - Something for you to watch

 

[kide]

Keith:
I'd be interested in your comments on the two most common problems I have with powder coated products.
1: Loss of adhesion. I've had lots of products from 5th wheel hitches, a expensive car dolly, motorcycle accessories, trailer frame and wheels, a Scag ZTR, etc. The only thing that's retained it's paint is the Scag...most of the other pieces of gear have slabbed off paint in patches. I believe the probable causes include inadequate surface prep (no"tooth") , wrong baking temp/time or ??. Usually you'll see signs of corrosion where the paints come off.

2: Dulling of the paint - waxing, etc. doesn't seem to bring it back.

I've wondered whether it's common practice to farm the powder coating out (where the guys <u>should</u> know their business) or if these manufacturers usually set up their own in house powder coating (where their expertise may be elsewhere). I looked at doing some myself (I've got a cheap outfit) and found lots of process documentation online - to the point of backing me off a little bit when it started looking like to do it correctly was a lot more detailed than DIY vendors would have you believe. BTW, don't worry, the parts will not be baked in the house..

 

[kadams]

While that is a great demonstration of what you can accomplish at home with very little equipment investment, it's a pretty candy-coated representation of hobby powder coating. Even the comment section for the video is loaded with absolutely wrong information. However, this is a good opportunity to set some facts straight.

Prep work is critical. They are right that you need clean, white metal. Media blasting is ideal, as it provides tooth for the powder to cling to. Degreasing is also extremely critical, but straight acetone or denatured alcohol are very effective, and generally much cheaper unless you are running a factory and coating the same parts day in and day out. Prep for outdoor parts can also benefit from zinc phosphate treatment.

They strayed far from the truth quickly, as you can most certainly end up with drips, runs, and dry spots, and it is very easy to apply too much powder. The good news is that if you mess up and know you got too much powder on a part, you can blow it off and try again.

Next, I have to point out that dry powder is sort of hazardous. Any volume of dust lofting in the air in sufficient quantity can make for a heck of an explosion. Also, it doesn't just lazily drift to the floor where you shoot it, it floats around your shop and eventually clings to things, because it holds a static charge. Your car, any metal shop tools, plastic items, and anything warm like heaters, light bulbs, or engines will attract the stray powder. You don't want it in your lungs, either.

While it is generally true that most powders cure at around 400 degrees Fahrenheit, you can't just time it for 20 minutes after it flows out. The cure parameters are dependent on the temperature of the part being coated, not the temperature of the air in the oven. You will undercure parts time and time again doing it the way they suggest, and undercured powder coat may look really nice, but it is as brittle as dollar store rattle can paint. The part has to be at the proper temp for the proper time, or the powder will not fully crosslink, and will have zero durability.

I don't think there are any other huge glaring flaws in the video, but I'm also typing this while on break from ripping shrubs out of my yard with my 147.

That said, it does show that coating small parts at home can be done, it can be done cheaply, and it can be done by anyone, plus it shows a really cool time lapsed recording of coat of powder flowing out. (And yes, the first few times you coat something, you will sit there and watch the part the entire time through the oven window.)

 

[kadams]

Gerry, those are good subjects. Those two issues are some of the big ones plaguing the custom coating industry today. I spend more time explaining why it happens and how it won't happen to their parts when I coat them than anything else. Some people still remain unconvinced.

<font color="ff0000">Loss of adhesion: As you've suggested, typically results in the finish peeling off in sheets. Generally, it is the result of poor surface preparation. Oil, dirt, or in the case of many of those corroded spots, corrosion was left on the part prior to the application of the powder. Things like cutting oil and mill scale are common on raw steel parts, but the rather effective method of media blasting is ignored due to time and cost. I don't think anyone here needs me to tell them that manufacturers usually only care about a product holding together long enough for the warranty to expire. Why make a powder coat finish last fifteen or twenty years when the warranty is up in one?

Other possible causes include powder that was applied too thin, or wasn't UV stable. Generally, modern manufacturers just phosphate and wash a part in order to etch and prep it. In my eyes, this is insufficient. I myself once had the powder coat lift off of a steel leg on a nearly new BBQ grill, and beneath the giant flake of powder was a perfect rusty thumbprint surrounded by shiny clean steel. In my mind, this is simply a case of things not being made like they used to be.

Of course, if a powder coated finish is compromised by a scratch, then corrosion can begin to grow beneath it, just like paint. This is where zinc phosphate treatment can be helpful, as it adds another layer of protection to the part both before it is coated, by preventing corrosion from getting a foot hold on the part prior to coating, and after the part has been placed in service in case the powder coat is chipped or scratched.

</font><font color="119911">Dulling of the finish: This one is almost always due to the use of an epoxy, or epoxy hybrid powder. They simply are not UV stable, and they turn dull and chalky in no time. Epoxy is the best powder coat ever for resistance to chemicals, and it is among the cheapest to buy, but it you have to treat it like a vampire. It's great for the battery box under the hood of a car, but if light gets to it, it's toast. I have a little Harbor Freight trailer that suffers from being epoxy powder coated. It looked good for about a month with it's shiny red frame, and now after sitting outside for a year and a half, it is flat pink.

</font><font color="000000">Another possible cause of both peeling and dulling is undercure. The line between really brittle undercured powder, and only slightly undercured powder that is fairly durable, but weathers poorly is a fine one, but it does exist.

From what I have seen in trade publications, large manufacturers frequently have their own dedicated powder coat lines in place on the premises, and several such lines are initially set up by outside vendors. Then there are contracted batch coating facilities that smaller manufacturers might use. Of course, with either approach, there are those that do good work, and those that don't, but the typical coating provided on mass manufactured goods today are done as cheaply as possible.

I believe your assessments on a whole are entirely correct. And don't be too afraid to start the DIY stuff. There are plenty of metal things around to practise on.</font>

 

[dtanner]

Keith C. Adams

I have been wanting to try some small parts with power coating . last year I paint a cat O on my 1512 Diesel tractor and see it has scratched and it has some bear areas. I did used a grease and wax remover and proper prep but did not like the end result and how it lasted(finish).I would like to try a hood off my 61 Original and the four rims because they will easily fit in an oven. I will have to look locally and see what is available as a kit in white . Thanks for your input . later Don T

 

[kadams]

Don T, I think once you give powder coating a shot and get the hang of it, you will be very happy with how well it wears. Just remember to start with clean white metal parts, and that having them media blasted is ideal for adhesion purposes. I happen to prefer 70 grit aluminum oxide.

Practise on something like cheap metal j-box covers first before you try the real parts, as it can take a few tries to get the feel for how to coat parts. Definitely avoid coating parts you care about at first, as stripping powder coat is a challenging ordeal, unless you want to invest in some hazardous, and somewhat expensive chemicals.

Beyond that, good luck! Feel free to ask questions here, and I will do my best to answer them.

 

[dfrisk]

KEN - When I was purchasing agent for the machine shop end of the steel foundry, we had some under riser cracking on an automobile shredder rotor end disc were were trying to arc-air & grind out and weld up. We used a 6 ft round by 2-1/2 to 3 ft tall galvanized cattle water tank turned upside-down and an LP gas heater to pre-heat the 4000# steel casting before we worked on it. It easily got the casting up to 400-450 degrees in less than an hour. The story doesn't end well though, we chased the cracks ALL the way through the casting and out the other side, through over SIX inches of alloy steel, so we had our "Friends" at the foundry cast us another one. The foundry put the bad one to good use, they used it by the shake-out pile to drop smaller castings on to break off the risers.

With the cost of LP gas or elec. heat, unless the enclosure was really tight the cost to maintain 400 degrees would get pretty high. And PC really should be heated with elec. heat. Flames create an air flow, plus would ignite the powder.

The Duplicolor engine enamel SON & I baked in the wife's gas oven we heated the oven to about 350-400 deg, shut the oven burner off, then put the valve covers and EFI top & bottom in the oven quickly and let them sit for a half hour. I suspect they got to 180-200 degrees and really cured the paint out nice, just about as tough as PC.

I'll continue to use PC for smaller stuff, and liquid paint on larger stuff. SON & I have experimented with base coat/clear coat with hardener in the clear coat and it's REALLY tough and durable too. SON found a manufacturer of BC/CC paints on-line a year ago that specializes in hobbyist coatings. The PPG stuff we've used so far is all for professional body shops where time is money. This place makes stuff thats more forgiving for the occasional user in less than perfect conditions. Plus it's quite a bit cheaper.

 

[dross]

Dennis brought up a question I've had for a while. I know everybody talks about useing an old electric oven. Can you use any heat source? I could see why a person wouldn't use wood but what abbout LP. Used with a separate firebox?

 

[kweaver]

Dennis - Have you ever walked on the wild side and done something experimental ?

<font size="-2">dang dog is barking at the dinosaurs again ...</font>

 

[kweaver]

Dave - I was just getting ready to draw up an "oven" with a kerosene heater (or propane burner) with an enclosed heat tunnel inside the oven to show Dennis how to get wild and get off the porch

 

[kweaver]

If I had Dennis' money I'd not worry about a one day cost to PC a Cub frame and rear housing ...

 

[kide]

The son-in-law's oven was about 2 feet deep, 5 feet wide and 5 feet tall.. IIRC, He built a quick frame out of 1" angle or tubing, covered it with old sheet metal pole barn siding, put on a layer of 2" fiberglass and another layer of sheet metal. It was on casters,so he could move it around. The entire front hinged open on it. He built hanger racks inside, put the oven elements, I think, on the back panel and ran the wiring out to the original stove/oven control panel. It heated up quick, stayed at a fairly even temp and he even had the oven timer on it! He was using it mostly for "yard art" that he was selling at craft fairs and wholesaling to other dealers.. I'm setting here looking out the window at a steel birdhouse that's at least 12 years old - powder coat still in pretty good shape. Sadly, he's sold the oven and equipment (he said he let it go pretty cheap)...

 

[kadams]

Propane is an excellent heat source. In fact, most large commercial ovens are gas fired and direct heated. I don't believe kerosene woould work well. When I rolled in to my first winter of powder coating in my shop, I used a kerosene/diesel salamander, and it contaminated the air in shop so severely that it brought powder coating operations to a complete stop. Every part came out with fisheyes. I had to decontaminate everything, and switch to electric heat.

 

[kweaver]

KCA - You didn't read Dave's post right , "With a separate firebox"

I was thinking of piping heat into and through an 8" stove pipe running through the "oven" for heat transfer. An oven thermorister can be used to control a relay for heat on/off.

No I wouldn't want any "forced air" in the oven.