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E-coating vs. Powder Coating vs. E-coating Plus Powder Coating

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A discussion started in 2003 but continuing through 2020

June 13, 2015

Q. Dear CED Experts,

I am new to this field of CED, Powder coating or painting.

Please advise me...
1. Which process is better, CED or Powder Coating for Truck or Bus Chassis.

2. Is it done before riveting / Bolting or after the whole frame is ready.

3. What is the coating thickness for Truck or Bus Chassis

4. What is the approximate per square inch cost of CED and Powder Coating for 8 Meter long chassis


Jagdip Punia
- Gurgaon, Haryana, India

June 15, 2015

Q. Hi Friends,

Recently I came to know that there are certain CED processes which meet the final Paint specifications, i.e., we do not need to do Primer, Top coat, etc.

Is there any such Technology called "Finish CED"?

If so, who is doing that? Please help.

venkat prabu
- chennai, India

June 19, 2015

A. Jagdip,
You didn't mention what spec you are trying to achieve. You also did not mention anything about pretreatment.
The CED and powder will only be as good as the conversion coating that is beneath them.
In my opinion, the best combination is a zinc phosphate pretreatment with a cationic epoxy e-coat primer AND powder.
The chassis can be e-coated with or without rivets and bolts. You'll need to consider masking and will also need to consider drainage as the chassis gets more complex.
Your paint supplier should be able to address film build and cost.

A. Venkat: The end use of your product will determine whether e-coat should be used as a top-coat. Cationic epoxies offer excellent salt spray performance but have poor UV durability. Acrylics have good UV durability but do not perform as well in salt spray.

Dan Mack
- Horicon, Wisconsin

June 19, 2015

Q. Please clarify what cost should be more -- Powder coating or CED coating (all the pretreatment process starting from Degreasing to Zn Phosphate will remain same)?


June 2015

? Hi Arijit. Please tell us what the parts are that you wish to coat (application, size & shape), and what the production situation is (x parts per hour, y hours per day, etc.)


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
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June 21, 2015

Q. Parts are 2 foot hollow tubes of 1 inch dia., production 200 per 8 hrs; shapes are a little bit bent (Turning Tubes of trucks. Please suggest which will be the best cost effective coating having same Zn phosphate pretreatment--CED coating black or Powder coating black.


June 2015

A. Hi again. 200 parts in 8 hours is 25 per hour or one every 2.4 minutes. This is a modest production rate and manual powder coating would probably be fine. It's also a low production rate for e-coating -- if the rack held, say, 4 or 5 parts, you'd only need to process 5 or 6 racks per hour. But you could integrate the e-coating with the phosphatizing, and probably would not be as easily able to integrate the powder coating with the phosphatizing.

My own feeling is that e-coating would be slightly less labor intensive, slightly less expensive in materials, and slightly more reliable (free from defects). The e-coating equipment would probably cost significantly more, so you would need the production run to last long enough to offset the capital cost difference.

Second opinions welcome, especially from anyone who has done both :-)


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
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September 7, 2016

Hello Everyone...

Trying to find out if I am doing powder coating after ED coating then how much time do I have to wait for doing powder coat over ED coating?

Please suggest if any effect of time period over the surface of coating.

Can you please suggest the best possible way to do powder coating inside the rectangular pipe of 1.5 meter long?

bhupender dabas
- Delhi,India

January 21, 2017

Q. Hello, I am representing a company which is involved in the manufacturing of fitness products. Not taking a much of your time my straight query for you is to know about best method to coat on kettlebells to protect them against corrosion? E-coat or powder coat (I know majorly)? Or any other process you can suggest.

Thanks and Regards,

Gunjan Soni
barbells - Vadodara, Gujarat, India

January 2017

A. Hi Gunjan. As one tiny part of your research I'll offer my opinion that powder coating will probably prove adequate. But what process do your competitors use and what do you think of their appearance, corrosion resistance, and durability? There is a stewardship issue here: I know a bit about e-coat vs. powder coating, but few if any of we readers is likely to have the experience and understanding of the kettlebell industry which should be brought into evaluating the alternatives. Good luck.


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
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January 22, 2017

Q. Hi Ted,

Thank you so much for the informative response. Our main concerns are their appearance and corrosion resistance. On this basis what would be the best method?

Thanks and Regards,

Gunjan Soni [returning]
barbells - Vadodara, Gujarat, India

January 2017

A. Hi again. I already answered your question -- powder coating should probably be okay -- but you didn't answer mine :-)

What finish do your competitors apply, and what do you think of it based on actual field experience? Scuffing, chipping, UV sensitivity? Exactly what appearance are you seeking? Once again, I'm pleased to give you a free off-the-cuff guess based on general industry experience, but what are you going to do with that guess? I don't know if you only permit indoor use, or they might be left out in the grass; I don't know if users bang them together and chip them; I don't know what grade of steel or iron they are made from. You can ask for guesses & hints for further evaluation, but that's about it :-)


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
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January 28, 2017

Q. Wonderful website you have here with so much information.

I have been working on a new invention (Patent has been granted) for a combination KettleBell/Dumbbell. I have been working with a foundry in China and after 3 different molds the design has been finalized and prototypes are being tested (1 year of work so far to get to this point). I have not been able to get them to detail the casting process. Per email, the material they are using is "fine steel sand". The prototypes have been made with "coarse steel sand". This makes me assume this is a sand cast process and not cast iron using a permanent mold. (?)

I am having challenges with determining a proper finish.

When I say "proper" I mean to imply that I am looking for a cosmetic coating to the equipment so that it will be a different color other than the standard gray/black you see in a gym. I am planning on using a candy apple red.

Current prototype samples they have sent were powder coated. The factory rep described the process as "electrostatic plastic spraying powder, and then heating frozen again". While the prototype was pretty, it chipped fairly easily on concrete. I tilted the item over at a 45 degree angle and then let it fall the remaining 6 inches to the floor... a 1" patch of coating immediately chipped off.

I'm looking for other options. I would hope that the factory rep would be able to give me suggestions, but communication and attention to detail has been a challenge so I'm trying to get "educated".

I am learning a bit about "e-coating", but it looks like there are many options within that realm. I would say the most important aspect is durability... what option will let 2 coated objects be banged together (not intentionally, but it happens) and not chip? Also envision this object being "dropped" to the ground from a 1" height, sometimes not on a mat, but sometimes on a concrete/garage floor. I'm sure some consumer will leave these outside at some point, but lets say that the finish is for indoor use only.

Dragon Door and KettleBellsUSA are some of the most durable in the industry in regards to online reviews about chipping. Their websites describes their finish as "Dragon Door's kettlebells are manufactured in China and are 100% cast-iron with a rust-resistant e-coat finish." "Kettlebells USA® make two kinds of e-coated kettlebells, Metrixx® Classic and Metrixx® Elite." Any thoughts as to what details their use of "e-coat" may be?

Of final note ... those two manufacturers state that their products are "cast iron" whereas my foundry may (?) be using steel sand. (This may necessary because of my design limitations that cast iron/permanent mold won't work... hence they chose steel sand/sand casting... again, they have not/will not confirm that fact) Any consideration in chipping with regards to finish on cast iron vs steel?

Thank you so much for your feedback, I hope the train of thought wasn't too disjointed or off the tracks. :-)

Jamie Kaszer
inventor - Carlsbad, California, USA

January 2017

A. Hi Jamie, thanks. Apple and companies like it which manufacture in China have full teams over there. You are unfortunately experiencing what people call "throwing it over the wall" -- you're going to get something, but you're not sure what, maybe cast steel or ductile iron or cast iron. Now you want to finish it, but don't know if it may have silicon embedded in it, nor what the mechanical finish will be.

You can specify zinc phosphating followed by polyester or epoxy e-coating, with a post-dye to give it a somewhat metallic red look. But it has to be something your casting contractor can accept responsibility for, as split responsibility is difficult to manage with domestic shops but will be impossible with you here and your contractors in China.

Alternately, you can retain a testing lab to try to reverse engineer the finish on your competitors' products, but we can't publicly comment on or speculate about what your competitors are doing beyond what it says in their sales literature because, as we've said on some other threads, we don't know the responders so we can't let posts here wander into potential crowd sourcing of industrial espionage :-)


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
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January 30, 2017

Q. Thank you Ted, completely understand about the "espionage" ... I am not looking to circumvent other's hard work. :-)
Some specifics in regards to your comments:
1) So the type of metal (cast steel/iron/with silicon) will have an impact on the adherence?
2) If cost were not a consideration, which process of finishing would allow the most chip resistance in the event of two weights being "clanged" together during a workout.
3) Same question as #2, but assume cost IS a factor... what would you recommend since we know powder coating won't suffice? (or does this circle back to the metal type issue to answer?)
4)I've read some of your threads on 7-tank phosphating... do you know if this type of finish is used in dumbbell/gym weights?

Thank you again for your help and empathy with my "over the wall" struggles.

jamie kaszer [returning]
- Carlsbad, California, USA

January 2017

Hi again. No paint adheres infinitely well -- it's always possible to scrape it off or chip it off in some fashion. But you are looking for fitness-to-purpose, not infinite adhesion, and e-coating on a surface which has been properly mechanically finished and properly phosphated should be fine.

3-step iron phosphating is probably good enough, but 7-step zinc phosphating is always better.

If silicon is imbedded in the castings, adhesion would likely be poor. Mechanical treatment like vibratory finishing will probably remove it; but an acid dip which includes fluorides might be required; I really can't say, and don't know whether others can without testing or not. Good luck.


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

March 3, 2017

A. I may have some answers, paint in general even E-coat will not adhere well to bare steel. To promote adhesion a treatment such as iron or zinc phosphate should be applied. A zinc phosphate coating forms through a precipitation reaction as the phosphoric acid at the boundary of the substrate is consumed resulting an increase in pH. Cleaner residue due to inadequate rinsing will also precipitate a zinc phosphate layer which will have poor adhesion which no subsequent coating will overcome. E-coat usually epoxy based will stick very well to the zinc phosphate. Actually epoxies will stick well to many substrates hence their use as adhesives.
As it appears you want a bright color, candy apple red, a finish coat would most likely be needed. Polyester would be a good choice or if you want a higher end coating with even better adhesion you could use a urethane. From what little I know of powder coatings, they tend to be applied thicker than a conventional liquid coating, adhesion may be adversely affected by this choice.
Good substrate choice, subsequent processing such as cleaning, treatment choice, and finally type of coating and application method could all affect adhesion.
I currently am employed on a coil coating process, the end product is stamped, bent, and/or rolled formed, and thus proving that a properly applied organic coating can have very good adhesion under some pretty brutal conditions.

Ronald Zeeman
Coil Coating - Brampton, Ontario, Canada

October 17, 2018

Q. Hi, I will be installing some trellises that include 11-12 mil e-coat powder coating, do they need to be field painted?

Sy Mtz
- Las Cruces, New Mexico, USA

October 2018

A. Hello Sy. If you have trellises that have been e-coated and subsequently powder coated (and assuming that it was done well and with proper pretreatment, and the top coat is not epoxy with it's poor UV resistance), that's probably a pretty robust finish. 11-12 mils sounds like a thermoplastic (teflon, nylon, vinyl) coating rather than thermoset. If you don't scratch them during installation, they should be fine. Are they aluminum, steel, or what?

We do warn though, that you can post your clearly understood questions here and often get good answers ... but if you post a question that you don't really understand, hoping the answer will help you understand the question, it may not work that way :-)

I'm not quite sure which is the case. Good luck.


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

January 6, 2020

Q. Is Powder coating [more] expensive or E-coating [more]expensive. In terms of the equipment, which process is [more] expensive.

Praveena Babu
Automobile Industry - Chennai, Tamil nadu, India

January 2020

A. Hi Praveena. I already offered my opinion above that e-coating involves more capital cost than powder coating; others are welcome to respond if they wish. But as already mentioned on this page and on the inquiry submittal form, our readers tell us they hate abstract questions, so I don't know if they will.

Your own actual situation is no doubt interesting -- please tell us about it :-)


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Ted Mooney, P.E. RET - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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