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topic 32574 p.2

Misc. problems in CED (cathodic electrodeposition) coating, p.2

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A discussion started in 2004 but continuing through 2020

February 17, 2015

Q. We are getting water spots and water or paint flow marks on the components after curing. We could identify the marks if we blow air after UF and before curing. How to eliminate these marks?

CED COATING UNIT - Hosur, Tamilnadu, India

CED Painting Defect: 'Partial Coagulation'

August 1, 2015

Q. Please tell me about the CED painting defect of "partial coagulation" on child bicycle parts like swing arm, center stand and prop stand.

prince Kumar
- gurgaon, haryana, India

Anodic to cathodic cell ratio in CED electrocoating

December 16, 2015

Q. Hi sir I want to know how much ratio in anodic and cathodic cell in CED bath

Sandeep kalidas raut
CED coating - Mumbai,Maharashtra, India

March 16, 2016

Q. How to calculate the anode cell ratio in CED? Please, I am preparing for an interview and I need a clear answer.

bala subramanian M
private automobile company - chennai, tamil nadu, india

CED Bath: Why/How has Sodium Increased with no other changes?

March 31, 2016

Q. Hello sir,
There is increase in the sodium content in the CED bath while all parameters of the bath are as per specification. Please suggest.

kalyani Argade
- Pune, Maharashtra India

simultaneous April 13, 2016

A. Na content increases due to carryover of alkaline cleaners from P.T. line. Rinse parts thoroughly.
Have you added any tubular part recently in your production?
If so, check the carry over.

Avinash Vidhate
- Nasik, Maharashtra, India

April 12, 2016

A. An increase in the sodium level can be due to drag out from your alkaline cleaner. Are you using a sodium hydroxide based cleaner?

Dan Mack
- Horicon, Wisconsin USA

June 27, 2016

Q. Hi
What is maximum oven temperature for CED jobs?
Can we put CED & Power Coated jobs into one batch for Curing the coatings?

Please give details.
Thanks & Regards

Vivek Nirgudkar
powder coating & CED coatings - Pune, Maharastra, India

July 7, 2016

A. Generally CED Paint cures at 150 °C / 20 minutes or 160 °C / 10 minutes Effective Metal Temperature. Oven Air temperature can be set depending on the Material thickness (Component) and time available for Oven curing.

If it is thin material may be 170 °C, 30-40 minutes more than sufficient to cure. In case of thick material like Forging or Casting we may go ahead up to 200 - 220 °C.

Logically we can bake both Powder and E.Coat in the same oven and there will be not any issue in the baking as long as if we meet the baking window criteria.

However E.Coating is a 'wet' process and it is cured in an oven to promote cross-linking. Solvent and Moisture evaporation takes place. Whereas in Powder, Curing causes the particles to melt and also serves as the catalyst for a chemical reaction that produces the desired finish. Both are different process.

During the Hot air circulation sometime loose powder particles deposits on the E.Coat surface before curing causes finish problem. Hence I would not advise Technically. Let us wait for some expert comment please.

Saravanan P.M
- Chennai, Tamilnadu, India

July 2016

thumbs up signHi. That sounded like "expert comment" to me. Thanks!


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

March 24, 2017

Q. How can we control roughness after CED coating? It is varying a lot. I want to maintain it to its standard.

monu mittal
- gurgaon, haryana, india

June 14, 2017



Anode Cell Area Calculation

October 7, 2017

Q. Can anyone please help me how to calculate the Anode cell area/ no. of Anode cells required in ED Coating process according to Area of Component or Tank size?

Also how to select the range of Rectifier?

Arunprabhu A R
Designer - India

November 27, 2017

Q. Can anyone please help me how to calculate the Anode cell area/ no. of Anode cells required in ED Coating process according to Area of Component or Tank size? How do we know what is the capacity of anode in relation to surface area? How much surface area is covered by one anode?

We manufacture wheel rims; when we hang these on a basket after CED coating some area is unpainted where they are touching each other. What is the real cause of this

Rohit Kumar
- Faridabad haryana ,india

Masking for CED Coating

January 22, 2018

Q. Hi
We'd like to mask the wheel rim knurling during CED process.
Please suggest any masking.

Felix prasad
- Chennai, India

April 11, 2018

Q. Hi sir,
I am having one small doubt regarding dot contamination (like popping). This only comes at body c-zone area, that means nearby the anode location.

Note: our dip coating system.

Suresh Nataraj
NEROLAC - Bangalore,Karnataka & India

Ed. note: Please forward a photo of the problem to for posting here.

CED coating defects

September 5, 2018

Q. Please explain the defects of CED coating.

sathish kumar
employee - india

September 2018

A. Hi cousin Sathish. More words please -- are you asking a previous poster to clarify the defects they reported so that you can help them? If so, thanks -- attempting to teach is perhaps the fastest way to learn -- but please be more explicit about which posting you are replying to.

If you are looking for help yourself, you can read this thread, as well as threads 23154, 38297, 51966, and 57561. You can search the site using the term "CED defect" for many more threads on the topic.

You can also obtain the two books about CED coating which were suggested higher up on the page. I am not aware of training courses for this subject is India, but hopefully Coatec India [a supporting advertiser] or a reader local to you will advise (please tell us your city because some areas of India probably aren't easily accessible to you). Best of luck, but be ready to invest at least a month of hard work in the study of CED defects :-)

Best of luck!


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

September 8, 2018

A. Dear Sathish, There are lots of defects in CED coating, as it's a very broad area.
But I will explain some defects which are usefully common for all CED Coating lines.
1) Paint Bubbles or CED bubbles :-
First of all CED is a continuous process. It's a non stoppable process. Whenever your conveyor getting stop this paint bubbles will come. this is a wet on wet process i.e. after dipping in ED bath it have mist spray to keep it wet, but some location are not covered in line, which show the Paint Bubbles issue.

D. Sharma
Paint Technologist - Aligarh,U.P., India

September 28, 2018

Q. We are doing E-coating for last 6 months and since last one week we are facing problems in the quality. Some lines appear after baking, and orange peel problems. The product doesn't have smooth finish, please help.

Ramakrishnan Iyer
Ganpath Electroplaters (Bombay) - Ludhiana-punjab, Indian

Ed. note: Photos to would probably help, Ramakrishnan.

December 2, 2018

Q. I'm using BASF ED paint. I'm facing a problem that high gloss level even I adjust the Pigment-Binder ratio.

- Chennai, Tamil Nadu, India

December 4, 2018

Q. Hi, my name is Harikishan. How to increase meq and conductivity of CED paint?

Hari kishan
Unique coater - Faridabad, haryana india
  ^- Privately contact this inquirer -^

January 11, 2019

Q. I want to know CED coating defects and its solution.

Satyam auto - Kannauj,up, India

January 2019

A. Hi cousin Abhishek. If you can explain a specific defect, include photos, and give data about the prevailing situation that led to it, I'm sure the readers will be happy to try to help!

Otherwise you can study this posting and its photos and dialogs, the other thread it steers you to (thread 57561, "Pin holes in CED e-coating"), find many other threads on the subject by searching the site for "CED defects", and review the two books which we have mentioned on the subject, and search for your topic on and It's unlikely that anyone is going to write a general tome covering the whole subject of possible CED defects and make it available to us all for free. Good luck, and get back to us with the actual situation you are confronting. Thanks.


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

CED coating adheres to sheet metal but not if zinc coated

February 6, 2019

Q. Dear Sir,

My question is on Zinc coated parts coated in CED. When we CED coat on sheet metal after maintain all process parameter then the coated parts pass SST (960 Hrs.) and Adhesion test pass; but on Zinc coated parts coated in CED then the parts do not pass the Adhesion test or SST.


Alok Ranjan Pal
- Ghaziabad, Uttar pradesh, India

February 2019

? Hi Alok. When you say "zinc coated" do you mean hot dip galvanized? Is the metal properly zinc phosphatized after the galvanizing?


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

March 26, 2019

Q. Hello sir,
We are struggling the problems on Pretreatment and Electrode deposition process. After completing this process we are facing so many problems like lints, air packs, E.D. drifts, flow marks, ash marks, etc. So anyone can please give me any solution for this problem. And give some parameters on E.D. paint.

Manikumar Surisetty
Paint shop - Andhra pradesh, India
  ^- Privately contact this inquirer -^

September 14, 2019

Q. Dear sir, after giving the coating in our bath, the coating is coming on half the tank. Conductivity of our anolyte is 1.500 and ED tank temperature .38

Himanshu Srivastav
- Fridabad harayanan india
  ^- Privately contact this inquirer -^

September 2019

A. Hi Fridabad. More words and details please! I'm not even sure if you are saying that the vat which is holding your bath contents is getting paint deposited onto half of it or whether the product you are coating is some kind of motorcycle fuel tank or similar and is being left half bare. Thanks.


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

CED e-coating bubbles/holes? Defect problem on chrome plated surface

January 18, 2020

Q. Hello Dear,

I'm custom finish coater.
I'm also trying to do some cathodic electrophoresis process (applied over nickel and chrome plated small objects like door handles, etc.).

I'm facing problem as in images, during epd coating (in epd tank) I get finish that has many Little little bubbles like inside it. Those micro bubbles are like in surface.

My process:
Degrease alkali
DI Rinse 2x
Acid pickle
DI Rinse 2x
Epd tank
DI Rinse 2x

I believe my substrate is okay because nothing happens in powder coating process so I believe nothing should happen in e-coat either.

Rafal Kolbu
- Brwinow, poland

January 2020

A. Hi Rafal. We did not get any images/photos; please e-mail them to

D. Sharma suggests above that a line stoppage is a common cause of this problem. Can you tell us whether the defect happens all the time or only some of the time? Chrome plating is not meant to be e-coated to my knowledge. Are you sure that you have good, functional, adhesion on the chrome?


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

January 18, 2020

Q. Hello,

That happens all time

I got detail movement in-tank. Chrome look Good, also I tried stress relief before e-coat too and that did not work.

Have no idea what is that, because it looks like something tiny air inside or maybe it's something else.

I tried different temp, voltage snd time setting.

I tried also powder coating same detail - for that everything is okay. Only e-coat goes bad.

On raw aluminium plate I also get that strange effect.
In touch that surface is smooth but has that small dot everywhere appearance

I wonder what steps should I take to find out problem?

I'm sending defects photos to my post.

32574-5a   32574-5c   32574-5b  

Thank You

Best Regards,

Rafal Kolbu [returning]
- Brwinow, poland

February 25, 2020

? Does this happen when you paint un-plated steel? I have seen where certain plated parts will outgas when e-coated.

Dan Mack
- Horicon, Wisconsin

March 17, 2020

Q. It happens on raw steel too.

Rafal kolbu [returning]
- Brwinow poland

August 1, 2020

Q. We are having Patches in CED Coating. Please suggest some remedy.


Upinder Singh
- Ludhiana Punjab

August 2020

thumbs up sign Hi Upinder. Thanks for the photo, but even with it I still doubt that anyone will be able to help you with no data supplied yet ... but we'll see.

Luck & Regards,

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

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