Home /
Search 🔍
the Site

Problem? Solution? Chime right in!
(perhaps the world's last 'no registration' site)


"What is paintlok?"

Current question:

March 3, 2021

Q. I have ductwork for a commercial job coming with a "Paint Lock" finish coat. I understand from this page it's meant for paint. I'm planning on using dryfall to lower the cost. I understand I don't need to etch it but is wiping it for oil with a cleaner still required? Newbie question here...thanks everyone!

Robert Morales
- San Juan Capistrano, California

March 2021

A. Hi Robert. If a lack of cleanliness is obvious, it certainly needs to be cleaned. If it truly looks pristine, then it's a judgement call but, personal opinion, I'd probably risk it since corrosion is not an issue, only poor adhesion ... and insufficient adhesion for this application doesn't sound likely if there is no visible dirt, grease, oil, or fingerprints. If we were talking about a car rather than ductwork, that would be very different of course.

Dryfall paint sounds fine for the application.

Luck & Regards,

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

Previous Q&A's on this subject starting in 2007:


Q. Hello,

This is my first time that I use this website, and I want to explain my situation. Yesterday I received a RFQ of one of my main clients, and there are few parts that needs a paintlok process. In order to keep the project I need to be able to treat those parts. I don't have any idea of what is a paintlok process, do anyone have a clue?

Thanks a lot for your time!

David Omar Gonzalez
Project manager of a powder coating line - Monterrey, Nuevo Leon, Mexico

simultaneous 2007

A. Paintlok is galvanneal. It's also called other things as you will soon find out. :-)

Sheldon Taylor
Sheldon Taylor
   supply chain electronics
Wake Forest, North Carolina



A. Paintlok* is electrogalvanized + phosphatized sheet steel. The coating is very thin, withstands most forming operations, has a dull gray matte appearance and is intended to be painted. ASTM A591/A591M [affil. link to spec at Techstreet], 'Standard Specification for Steel Sheet, Electrolytic Zinc-Coated, for Light Coating Weight [Mass] Applications,' with supplemental phosphatizing specified, can be used to order the material. Possibly, Paintlok corresponds to the A591M 'Intermediate' thickness of 0.84 microns (6 g/m2) zinc per side. Weirzin Bonderized is ~equivalent.

*The ELECTRO PAINTLOK® trademark was issued to Republic Steel in 1942 and apparently belongs to Mittal Steel (although not found on their website).

Ken Vlach [dec]
- Goleta, California

contributor of the year

Finishing.com honored Ken for his countless carefully
researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work
which the finishing world continues to benefit from.


October 27, 2012

Q. A previous answer describes that it "is intended to be painted"

My question is, if I were to paint on this material, do I need to prime it first, or can I paint directly on this dull gray surface?

I'll be using one shot enamel, the sign will be outdoors, for 6 months in Southern California.

My client purchased this product and wants us to paint on it. Not my first choice but I can work with it.

Any help greatly appreciated!

Bear Brady
Sign Painter - Los Angeles, California USA

October 28, 2012

A. Hi, Bear. I think a phosphatized finish will accept paint very well, and it sounds like the trademark was deliberately selected to imply that paint will adhere well. But it's still a truism that two coats are better than one, due to greater thickness, reduced porosity, and less chance of missed spots.

Good luck.


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

November 4, 2012

thumbs up signI've started the job and 1 shot seems to be holding well.
Thank you for the reply.

Bear Brady
- Los Angeles, California, USA

January 27, 2014

A. Galvannealed (which PaintLok is a type of, specifically ASTM A653 [affil. link to spec at Techstreet] Coating A60) is very similar to Galvanized except it uses a zinc-iron alloy rather than just zinc. Both are per ASTM A653 (which has replaced the previously mentioned A591), with galvannealed being a coating designation of A or ZF and galvanized a G or Z designation.

Electro-Galvanized (ASTM A879 [affil. link to spec at Techstreet]) is another variant of corrosion resistant steel sheet.

Both Galvannealed and Electro-Galvanized are readily formable and weldable with no need to remove the coating. Both accept paint well.

Normal Galvanized (ASTM A653 any coating G or Z) does not accept paint well.

Some commercial references:


Dan Harlan
- Chandler, Arizona, USA

April 2, 2015

Q. I am a sheet metal worker. My brother asked if I could use Paintlok galvanised to top an island he is building for his wife. I am nervous about this as he does not want to coat it. Can this product be used uncoated for a counter top? Thanks.

mike cowan
- garden Idaho USA

A. Hi. I'd say no. It's not meant to be, and it's probably not the kind of food-safe finish you would want on a kitchen counter.


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

August 15, 2016

Q. I am an mural artist used to painting on walls. My client (a librarian) wants me to paint the (wood) risers of her exterior front stairway to resemble a stack of books. We have decided the best way to do this is to paint sheets of 20 guage sheets of stainless steel (cut to size), one per stair and then adhere them to the risers.

I plan to use PaintLok steel, and then it sounds like I should seal each piece. What product do you suggest?

Then for the paint, I was planning to use exterior grade latex. I am worried about top coating it with something else to finish - I don't want it to yellow over time or appear too shiny. But will it stand up over time without it? How many years should she expect the work to last?

Then last but not least, I am planning to use liquid nail to glue the sheets in place.

Does this all sound like a good plan? Any help is much appreciated!

Kristina Young
Muralist/ Mosaic Artist - Napa, California USA

Powder Coating of PaintLok steel

January 30, 2017

Q. Hello,
I was reading this thread and had a question to add of my own.
I run a Powder Coating Department and we run across some issues when applying powder to Paintlok. I searched the web to find answers to why we are having this issue. Please help!

thank you,

Val Leedy
- Chino, California, United States

March 26, 2017

A. Hi Val,
What issues are you having? Be sure the parts are clean, dry and oil free! Powder coating does fine on Paintlok in most cases.

blake kneedler
Blake Kneedler
Feather Hollow Eng. - Stockton, California

December 10, 2020

Q. Is it necessary to wash paintlok prior to powder coating?

We powder coat CRS in various gauges. Parts cleaning is always a constraint. We use a self made hot water mixture with zirconium and it works well, but we were told Paintlok does not require cleaning, so we can take it from the laser direct to the powder coat booth. Is that correct?

Ron Vinyard
- Pacific Missouri

A. Hi Ron. Reputedly, the galvannealed finish of "Paintlok" does not need phosphatizing pretreatment. But to say it doesn't need cleaning could be a stretch: anything that isn't clean needs cleaning, and unless you're sure the product is fresh from the mill and untouched except by properly gloved operators, that's questionable -- as you can see from the previous question :-)

A second issue is that we should really reference material in terms of accepted specifications like specific grades per ASTM A653 [affil. link to spec at Techstreet] rather than a trademark from 75 years ago because we can run into a similar situation as we would in trying to quantify the adhesion or tensile strength of "scotch tape". When the two different spellings 'paintloc' & 'paintlok' are used interchangeably throughout an industry, it's evidence that we're really not talking about the trademarked product anymore but slang, and it isn't possible to demand that it comply with our expectations.

A third issue is that I unfortunately don't know what you mean by "the laser". If you are cutting steel sheets/plates with a laser and doing no pretreatment on the raw edges, that can certainly introduce problems.

Luck & Regards,

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

this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread SEARCH for Threads about ... My Topic Not Found: Start NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

Chemicals &
Consult'g, Train'g
& Software

About/Contact    -    Privacy Policy    -    ©1995-2021 finishing.com, Pine Beach, New Jersey, USA