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"Remove / Strip Zinc Plating from Steel"



2005

Q. Hi.
I work in roll manufacturing company. Recently I got a job about removing plated zinc on steel roll. Roll Dia. is about 30", face length is 54" and about 80" long including shaft.
Zinc is plated over the entire roll. I don't want any hazardous method, which causes my workers to get sick or makes the environment poisonous with zinc oxide.
I decided to heat the roll in tampering furnace to 450 °C (790 °F) and melt the zinc (Melting point of zinc is 780 °F). I will appreciate any comments, suggestion, other easy methods, or advice.
Thanks.

Kashif [last name deleted for privacy by Editor]
Manufacturing Co. - Chicago, Illinois, USA
^


2005

A. Kashif: STOP please!

That sounds like a completely ineffective method to strip zinc from steel because the zinc plating is thin, and the steel will remain "wetted" with it; think of hot-dip galvanizing where the zinc sticks to the steel. Plus, the heat is possibly dangerous, environmentally questionable, expensive, and wasteful :-)

"The whole aim of practical politics is to keep the populace alarmed (and hence clamorous to be led to safety) by menacing it with an endless series of hobgoblins . . ."
H. L. Mencken

Opinion! Rant mode on: Such ideas "for safety" are the harvest of the chemical paranoia that our governments spend so much of your tax money sowing.
Although welders who weld galvanized steel without proper ventilation can inhale clouds of vaporized zinc oxide and get an overdose, resulting in metal fume fever, zinc is not a poison -- it's an essential nutrient. Cold prevention tablets are such zinc salts. Rant mode off.

Zinc is readily and almost instantly stripped in relatively mild acids like inhibited muriatic acid (hydrochloric acid). And other methods like reverse plating are not difficult either if acid immersion is inappropriate for this roll. My question is: who applied the zinc plating? If it was not done in house, then the stripping should probably not be done in house either. Any plating shop capable of zinc plating rolls will be capable of safely stripping the zinc plating. Best of luck!

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



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



2005

Q. What is the best way to strip Zinc plating, leaving the Sheet steel substrate in a condition where it can be re-plated?

Peter Francis
Design Engineer - Chelmsford, Essex, UK
^


2005

A. Immersion in a hot caustic solution or room temperature hydrochloric acid will remove the zinc. Your electroplating contractor should be able to do this prior to replating.

Dougie Lightfoot
- Fife, Scotland
^


A. Dougie is exactly right. When production platers happen to produce a part where the zinc plating is unsatisfactory, they generally don't have to do any specialty stripping at all -- just running the part back through their usual alkaline cleaner and mild acid dip strips the zinc plating.

Luck & Regards,

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



How to remove zinc plating from steel bolts

2006

Q. I would like to know the process to remove the zinc plating from some bolts. This is needed so I can paint them for an old car restoration.

Jim Butterbaugh
Hobbyist - Tijeras, New Mexico
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2006

A. Zinc is quickly stripped in Muriatic Acid [affil. link to info/product on Amazon] . However, this acid is somewhat dangerous for an untrained consumer, the fumes can ruin any metal nearby, and you'll be left with a hazardous waste to deal with. There is also a good chance of hydrogen embrittlement of the bolts. Better would be to find painted or black oxided bolts, and if that isn't possible, to send them to a plating shop for stripping (may cost more than you like). Best of luck.

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



Will electrolysis (reverse plating) remove zinc plating?

2004

Q. I wonder if it is possible to strip the zinc layer from zinc plated bolts by electrolysis in a profitable way.

I have to strip zinc plated material, but I want to find another ways rather than just using sulphuric acid. Therefore I wondered If it is possible strip this material in a zinc plating electrolyte meanwhile I connect it to the anode instead to the cathode?

What would be the risks and the damage to the substrate material (steel) by doing this way?

Thanks a lot and my best regards.

Guillermo Castorena
Plating Shop - San Luis Potosi, SLP, Mexico
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2004

A. We use HCl to strip zinc from steel. You can use sodium hydroxide too. Why use power when it's unnecessary?

Steve Clark
- Belfast, Maine, U.S.A.
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2004

A. Acid stripping is bad news for hard bolts. Hydrogen embrittlement is a very strong possibility. Bake (soon) after strip if you do. Caustic is slower than acid, but it also has a lot smaller risk or attacking the steel. Electrolytic will speed up the operation, but costs more-- a tradeoff.

James Watts
- Navarre, Florida
^



Stripping zinc plating in preparation for E-coating

March 10, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi All,
I got some parts with zinc plated surface and customers would like to remove the surface and replace by E coat. Currently I'm using HCl 30% to remove the zinc layer but it is too strong, and residue leftover causes high rejection. Can any Mr. Expert give me some guides or better methods?
Thanks

KC Tan
- Ulu Tiram, Johor, Malaysia
^


March 2014

A. Hi KC. We appended your inquiry to a thread which suggests some other methods, but my question would be why do you need to remove the zinc plating? If the plating is not defective, I think it can be a good base for the e-coating, and will offer sacrificial protection. If you remove the e-coating, you will have to phosphatize the surfaces before e-coating. Good luck.

Regards,

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


March 11, 2014

thumbs up signGreetings Mr Ted,
I understand your concern but customer insists on cosmetics. This zinc layer if not removed will form "wavy" surface after E-coat, which is considered as NC regardless how good the adhesion.
Thanks

Kc Tan [returning]
- Ulu Tiram, Johor, Malaysia
^



Can I use NON Fuming HCl to strip reusable zinc plated steel parts?

May 30, 2014

Q. We would like to use a lower concentration of HCl that is NON fuming for the safety of our personnel. I would like to find out if the bath will still be strong enough.
We are currently using 110 gallons of 20 baumé and 160 gallons of water.
If we can, are there any recommendations of concentration and quantity of the HCl and the amount of water to add.
Thanks.

Daniel Andreson
Plating shop - Oklahoma City, Oklahoma, USA
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October 19, 2018

Q. Possible to use Citristrip to pull zinc plating off screws? Need to patina the heads after zinc removal. Thanks!

R. Anders
fabricator - Oakland California
^


October 2018

A. Hi R. Anders. The SDS for Citrustrip mentions only organic chemicals, rather than acid or alkali, so I doubt that it will work. But there's a saying among bridge players that "a peek is worth a hundred finesses" : some things are easy enough to find out that it may not make sense to spend a lot of time in speculation :-)

Regards,

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


October 22, 2018

Anything with "Citri" in the name generally contains either citric acid or d-limonene (a.k.a. citrus oil). Citristrip calls itself a paint and varnish remover, which says "solvent" to be, which of the two options would be the d-limonene.

Citric acid and citric acid based products aren't that difficult to come by, though, nor is citric the only option for stripping zinc. Any mild acid should work fine, including acetic acid (a.k.a. vinegar).

ray kremer
Ray Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
stellar solutions banner
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