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Metal finishing Q&As since 1989


Powder adhesion on red oxide surface and primer

Q. We have gear housings that in the past were red oxide on the inside to prevent any oil from leaking through the casting. I have been told that we can use powder coating to replace the red oxide and achieve the same or better results.

Is this correct?
Is powder coat impervious to all oils?

Brian Villareal
manufacturing / engineering - Durham, New Hampshire

"High Performance powder Coating"
by Bob Utech

on AbeBooks

or Amazon

(affil links)

A. Hi, Brian. Powder coat is not actually a material, it is an application method: finely powdered plastic is sprayed onto the parts, and sticks to it by electrostatic charge; the article is heated to melt/fuse the plastic into a coating on the article.

The point of making that distinction is that there are many different powders available, including epoxy, polyesters, nylons, vinyls, and teflons, and I'd be quite confident that -- with a supplier's help -- one can be chosen that will be completely resistant to the oils. Good luck.


Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey

Q. Sir,

I wish to know that if the surface is covered with red oxide primer (ORDINARY,THAT IS USED IN WET PAINTING ALSO), will it be detrimental of beneficial to the quality of final coated product. In order to fill in small holes and crevices my customer fills in primer only on that area which is just a small portion of the piece, will I get fine results?

Thank you.


metal crafts/powder coaters - BATALA, Punjab, INDIA

A. "Red-oxide" primer will not be able to withstand temperatures of 180 to 220 °C encountered in any powder coating. With the primer failing at such temperatures, the top coat viz., powder coating, will also fail. Please consult your powder supplier and select a compatible primer which would enhance protection of the substrate even in the case of scratches and minor damage to the top coat. Also beware of some suppliers giving you "Gheru Mitthi" or saffron clay in the name of red oxide!

Srinivasan Subrahmaniyan
- Indore, M.P., India

A. Please contact your supplier. There are pre coat powders available just as primer to wet painting. You need to coat the precoat powder at 180 degrees for a specific time depending on the thickness, and go for the required finish coat.

- Kuwait

Corrosion-resistant, paint-type finish for iron door-frames to be used by untrained manpower

Q. We are a facility management company, principally looking after residential complexes. We are located at Bhiwadi, on Rajasthan-Haryana border. In last five years, this region has seen more than ample rain and this has given rise to a new problem in maintenance which is frequent rusting of door-frames. Needless to say, the problem is more severe in the ground floor houses. This has cost us several thousand rupees in last two years alone on several liters of paint and primer.

We are hoping to find a better solution than re-painting of door-frames, from companies with active R&D. Is there a coat/finish that can prevent corrosion for a period longer than three months and is as easy to apply as any normal paint? If yes, please inform us.

Thank you for your precious time. we do understand that as a consumer-level enquiry, this may not elicit much interest, but help from your industry would be a great one for our industry as a whole.

Thank you.

Ms Aradhana D [last name deleted for privacy by Editor]
(construction and maintenance of complexes) - Bhiwadi, Alwar, Rajasthan, India

A. In Australia ,
Door frames of steel are usually hot dipped galvanized and they last for many many years , usually they require painting only when the colour of the house is changed , but the process is expensive .
A cheaper alternative would be Zinc Electroplate with a yellow chromate finish

John Tenison-Woods
John Tenison - Woods
- Victoria Australia

A. The downside to the galvanizing or the electroplating is that you wouldn't be able to (at least, not economically) do it on-site. And certainly not with untrained manpower.

Try looking into rust converter [on eBay or Amazon (adv.)] - these are paint-like products that convert the rust already present on the door into a very corrosion resistant and not horribly unattractive finish. If you search through the archives (or enter the following google search - ""), you should be able to find more information.

Good luck!

Jim Gorsich
Compton, California, USA

A. Hello Aradhana;

The pretreatment of Mild Steel is rarely done well in India; most people use a powdered red oxide which is a powder that falls off the steel. When this red oxide powder is mistaken for a primer and directly painted upon; is where we go wrong.

You can't get down the line and stop this, so your best bet is to use Hot dip galvanised or zinc plated sections and use a zinc chromate before you paint.

Khozem Vahaanwala
Khozem Vahaanwala
Saify Ind
supporting advertiser
Bengaluru, Karnataka, India
saify logo

March 5, 2009
"Fundamentals of Powder Coating"
by Society of Manufacturing Engineers

on AbeBooks

or Amazon

(affil links)

A. Dear Aradhana,

We also face these problems. What I suggest is the newer Al and Zinc powder paint to be painted on the door frames. Being involved in this development work we have more solutions with different kind of products.

Take care


Pradeep Mittal
- New Delhi, Delhi, India

Enquiry for setup of red oxide plant and purchase of machinery required

March 16, 2008

RFQ: 1. What is the procedure for producing red oxide. How I will set up a plant of red oxide?
2. Where I will get the machinery ?
3. What is the cost of setting up a new plant?
4. Who deals in the machineries required for this plant?
5. How is the raw material purchased and transported ?
6. Where from is the raw material purchased?
7. What is the method of packing the finished material?
8. What is the end use of the finished Zinc Oxide?
9. Where in India do I contact for more information?

Kishore Bodempudi
Buyer - India

Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)

Distemper and coating

Q. i am student of chemical engineering recently I completed my BSC now I am interested in distemper, weather sheet, under coating (red oxide). I also try some batches but I want more good quality formulation for this please suggest me if any one has experience.
I shall be very thankful to you.
Thanks for the use of this site.

farhan ali
- Pakistan
August 8, 2016

? Hi Farhan. I have heard of the word "distemper" to mean "anneal" (sort of the opposite of 'temper') but I don't think that is what you are referring to.

I think 'distemper' is also a coating used on artistic paintings, but I am not familiar with what it actually is. We'll have to wait for a reader with a better understanding of the subject than me :-)


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
August 2016

A. When I was young - a very long time ago - distemper was the common name for water based domestic paint.
But we still have no idea what you are trying to achieve.

geoff smith
Geoff Smith
Hampshire, England
August 9, 2016

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