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-----:Remove rust from zinc plated steel without damaging the plating
Quickstart:
Zinc plating is used to protect steel from rusting. It not only helps the steel resist corrosion by coating it, but it sacrificially protects it as well. Zinc is cathodic to steel, so as corrosive forces 'steal electrons' from the steel, the steel is able, in turn, to steal electrons from the zinc so the zinc corrodes rather than the steel rusting.
Given enough time and exposure to the atmosphere, a glassy zinc carbonate surface can develop which is highly corrosion resistant, so very heavy zinc coatings such as applied by hot dip galvanizing can last 50, 75, even 100 years with no maintenance. But if galvanized objects are wet and not open to good air circulation the zinc will corrode as 'white rust' or 'wet storage stain'.
Zinc electroplating is much thinner and less corrosion resistant than hot dip galvanizing, so the zinc is invariably given a chromate conversion coating to deter white rust.
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Q. looking to reduce white rust
any help is much appreciated
Jamie
Jamie
hobbyist - Hollywood , Md
February 16, 2026
This is a meeting place for camaraderie & sharing, not a free consultancy. So some readers don't engage with anonymous posters.
A. Hi Jamie
Unfortunately your question is too abstract to be able to offer much help. Do you have a boat trailer that is corroding, or are you experimenting with home-brew zinc plating and are unhappy with your results, or what?
For the homemaker/handyman the best answer is usually to apply rust converter and then paint the object if paint is not inappropriate for it. Get back to us with your situation please.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
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⇩ Similar, related, Q&As -- oldest first ⇩
Q. Hello,
I'd like to find an efficient method for removing rust from zinc plated steel i.e. (bolts, screws brackets etc) without removing or damaging the zinc plating. I've tried using different kinds of acids -- phosphoric, hydrochloric, vinegar
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Amazon [affil link] , C-L-R, in varying dilution ratios but the zinc is always destroyed. I was wondering about the process of chelation, where, if my understanding is correct, doesn't use acid to remove the rust. If chelation is a viable option, what is an efficient way to use this process.
thank you
mary
car restorer - rochester, New York USA
February 10, 2016
A. The zinc was originally plated on the article to prevent it from rusting by sacrificial protection; in other words, zinc, being more active, will dissolve preferentially to protect the steel. And that's what happens when you put the article in any acid. If you're seeing red rust it means most of the zinc is already gone, having performed its' purpose. One option is to have the part replated; another is to strip the part of all coatings and apply zinc-rich paint, and a third option (often the most effective and least expensive) is to buy a replacement part.
Tom Rochester
CTO - Jackson, Michigan, USA
Plating Systems & Technologies, Inc.
Q. Tom, thank you for responding to my question. I have a follow up question. I'm in the process of doing an experiment to see how quickly zinc plating will dissolve using three different diluted mild acids. Here are the acids I used: 1 pt white vinegar to 1 pt water, 1 part CLR to 1 pt water and 1 pt molasses to 10 pts water. I placed a zinc plated fastener (all the same) in each container. Here are the results so far:
Vinegar/water -- zinc completely dissolved in 1 hour
CLR/water -- zinc dissolved completely in 15 minutes
molasses/water -- no change in zinc 24 hours & counting
I just realized I didn't ask the follow-up question that I referred to in my previous post. Here it is ...
I would like to be able to clean and remove any signs of red/brown rust from small zinc plated parts i.e. fasteners, brackets, clips, etc. and leave as much as possible of the zinc plating intact. Based on my experiment (last post) it appears that the molasses/water will accomplish this. Do you agree or would you recommend something different. Thank you for you assistance. It's much appreciated.
- rochester, New York USA
February 10, 2016
Ed. note: Molasses is indeed reputed to chelate rust but the process can take weeks.
A. Try 5 % ammonium citrate, ph 3,5 (dissolve 50 gms citric acid
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or
Amazon [affil link] in 1 liter water, add ammonia
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Amazon [affil link] until pH is 3,5!!!).
Hope it helps and good luck1
- Zagreb,Croatia
February 11, 2016
Q. What about rust removal from the I.D. of tubing that has been zinc plated. The integrity of the plating itself on the O.D of the tube is fine. It is rusted on the I.D. because of the heavy stripping process in preparation for plating has attacked the raw I.D of the tube and thus rust. How do you remove that type of rust and not attack the plating on the exterior?
Russell Ahrens- Sturgis, Michigan USA
February 19, 2016
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A. Hi Russell. If the tubing is zinc electroplated it is highly unlikely that it ever had any zinc plating on the ID, with the exception of the first half inch or so (depending on the diameter).
I don't think you'll find really good chemical or electrochemical ways to remove rust without attacking the zinc plating, although you could try Goran's ammonium citrate idea. I think you will be better served with some sort of masking operation whereby whatever you do (sandblasting, acid dip, alkaline derusting) is restricted to only the rusty bare steel inside of the tubing.
Without any info on the tubing length or diameter, this answer sound either appropriate or silly, but maybe plugging one end of the tubing, filling it half way with appropriately sized gravel and a phosphoric acid based rust converter solution, then plugging the other end and shaking it would work.
In the future it may be possible to phosphatize and oil the inside of the tubing immediately after plating. That way the aggressive rust-removing acids would be applied before the zinc plating process. Thus the potential process might be: soak clean, electroclean, acid dip, zinc plate, chromate, phosphatize, oil (with rinses between each step). Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Need quick confidential answers? $25
Need project assistance? $100/hr.
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