-- The Home Page of the Finishing Industry
  HOMEFAQsBOOKSHelpWantedAdvertiseContactFORUM Letter 34446

The Hotline: Serious Education ... plus the most fun you can have in metal finishing. Ted Mooney, Webmaster

Muriatic acid stains on stainless steel



By mistake yesterday I splash with the mop a few drops of Muriatic Acid [linked by editor to product info at Amazon] solution (water diluted) on the freezer of a house we were repairing the grout, we didn't notice the accident until today that the owner of the house call us a let us know she have small yellow marks on the stainless steel door of the freezer. What can I use to remove those stains?

Andrew Costas
contractor - Bay Harbor Islands, Florida


Fine grain steel wool, work with the grain/finish. The stains shouldn't be too deep (you can also use brillo pad).

Marc Banks
Blacksmith - Elizabeth City, North Carolina, USA


DO NOT use steel wool or Brillo Pad unless you want to have a rust problem.

Use only a NON iron containing material like Scotchbrite(TM) or fine grain emery paper or the like.

lee kremer

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois


We are remodeling our home and have just discovered what we think are tiny acid stains in our brand new sink. They are numerous, tiny and appear to be pitting the surface and have not come out with the usual commercial products available.

What can you suggest as a next step?

Kate McCaw
- Summerville, South Carolina

March 18, 2008

I've had experience removing muriatic acid stains from stainless steel. A metal finishing specialist once told me to use "Barkeepers Friend [linked by editor to product info at Amazon]", a cleanser readily available in stores, with a cloth or sponge. It's non-invasive and is the best first step. I was amazed how well it works with a little elbow grease and a few applications. I've used it a couple times without the need for abrasive pads like emery cloth or sandpaper. These would only be second options as they can change the grain of the finish. Spread the word. It's a little known secret that works.

Tom Black
Tile Contractor - Woodinville, Washington, USA

August 30, 2010

I sprayed my gas stove with Mr Muscle kitchen Cleaner, became busy with some other work, went out on errands and forgot all about it till I returned home late at night! I was shocked when I went to switch on the gas to find it all stained. I tried CIF, more Mr Muscle, plain soap and water - and even ash! nothing worked - the stains make the stove look so dirty - please help someone and tell me how to get the shine back!

tonee Patil
Distressed Housewife! - Bangalore, Karnataka, India

April 22, 2011 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Stainless steel kick plates on mahogany-colored wooden doors look impressive in any business setting, until floor finish or stripper from adjoining CVT or seamless floor covering is accidentally splashed onto the bottom of kick plate. Cleaning crew tries Windex, which has ammonia, and leaves all kick plate shining except for the bottom that is stained. Keep working on the panel and eventually it takes on brownish streaks with or against the grain. Seemingly the more the panel is wiped, the worse it gets. Brownish scares me. Makes me wonder if it is starting to rust. Had a similar problem with grab-bars in hospital restrooms. Everything had to sprayed or wiped with a germicidal cleaner/disinfectant for infection control. The product does a good job killing germs, but it also kills the luster of the stainless steel grab-bars. First little brown spots appear. Is it possible that stainless steel is not always stainless, or can those brownish stains be worked out? I saw an empty Mineral Shock bottle sitting around somewhere. Would that item possibly be on of the suggested cures, and worthy of purchase?

Don Corbin
Building Maintenance - Albany, Georgia


For all those questions regarding acid staining damage on stainless steel surface, Scratch-B-Gone is the proven solution for the discoloration and rust stains. Makes fast resolve to this unsightly problem while protecting the surface from re-staining.

Barry Feinman

Barry Feinman
Restore It Yourself, Inc

Carlsbad, California

Did maids or someone else cause stainless appliance to blacken?

August 6, 2014

Q. I was wondering what chemical reaction would cause a stainless steel oven to turn black in areas on the outside? The owner is blaming my company, but we don't carry acidic chemicals in our supply. I do know that the painters had been there as well and had a pump sprayer with them (most likely of muriatic acid but I am unsure). It looks as though something was sprayed on it and dripped down between the knobs. It is black almost as if it were burnt.

Would bleach cause that, or something with bleach in it? The owner claims it turned black very quickly. From what I have read, bleach would have to be used over and over or left on for a long period of time. We were only there once, and whatever the young lady used was wiped off right away.

Susan Ellis
Janitorial - Northport, Alabama USA

July 2014

A. Hi Susan. A photo would help, and if the owner is not willing to let you take a photograph, I don't think you should be willing to offer anything when you don't have reasonable grounds to suspect an error on your own part. Looking at the "trails" may help indicate their origin. If the trails are only below the knobs, it's hard to blame painters, tilers, or anyone else but you or the homeowner or some other janitorial service.

Bleach is bad for stainless; the stronger it is, the worse. Some other cleaners like "Zap" and "CLR" and "Lime Away" are also probably bad for stainless. Good luck.


Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

August 6, 2014

Q. The blackening starts at the top ledge of the oven above the knobs, where some people set trinkets or salt and pepper shakers. The trails are wavy and run down between the knobs.
From what I have seen the "stainless" might be a different type of metal.

The blackening is similar to what happens to aluminum when it comes in contact with muriatic acid. As you can kind of see in this video:

I'm not sure if the owner will let us take pictures or not, he is pretty irrate. He said he was going to send before and after photos, but has not provided those. The property was kept unlocked for several days so that repairmen, painters and cleaners could come in.

Susan Ellis [returning]
Janitorial - Northport, Alabama USA

August 25, 2014

A. Susan,
Bleach is bad for stainless, muriatic acid is much worse. Any etching or staining that has a distinct splash or drip appearance generally is exactly that, the result of a strongly corrosive chemical getting onto the stainless surface.

Stainless that is regularly cleaned with bleach will suffer eventually, but the corrosion will be more evenly distributed. The other common thing is muriatic acid floor cleaners giving off fumes that attack the lower portions of stainless steel appliances.

Ray Kremer
Stellar Solutions, Inc.

McHenry, Illinois

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It is not possible to 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; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & DevicesUsed & Surplus

©1995-2015     -    Privacy    -    Search