Cleaning Stainless Steel?

PhotoSmith · Aug 11, 2007

I have a few stainless steel sheet film hangers, and 8x10 SS processing tanks that have a bit of rust starting on them. What is the best way to clean them? Once they are cleaned do I need to do anything to the stainless steel to protect the effected areas?

Thanks.

Samuel Hotton · Aug 12, 2007

During the 1970s, I used to coat the stainless steel sinks with a light coat of Oil of Wintergreen after cleaning.
Sam H.

Dave Miller · Aug 12, 2007

Rust indicates that it is poor quality stainless steel, but if it can be cleaned off I think it will simply be a case of periodic cleaning to keep it clean. The danger is that any protection applied may interfere with the chemicals used.

Samuel Hotton · Aug 12, 2007

Most of the problems with rust came about by somewone using plain steel wool OR a non-stainless steel object like a blue steel razor blade to clean with. Any object with iron in contact with stainless steel will corrode it. High concentrations of Iron in the water will etch spots on stainless, if left in contact. The best answer I know is to wash and dry when done.
Sam H.

PhotoSmith · Aug 12, 2007

Samuel Hotton said:
Most of the problems with rust came about by somewone using plain steel wool OR a non-stainless steel object like a blue steel razor blade to clean with. Any object with iron in contact with stainless steel will corrode it. High concentrations of Iron in the water will etch spots on stainless, if left in contact. The best answer I know is to wash and dry when done.
Sam H.

Thanks Sam. I just purchased these items used and they are in great shape except for a few minor spots. Would Bon Ami cleaner or a Scotch Brite pad be OK to clean them with?

resummerfield · Aug 12, 2007

I clean my sink and tanks with Comet cleanser and a ScotchBrite pad.

Bob Carnie · Aug 12, 2007

I do too

resummerfield said:
I clean my sink and tanks with Comet cleanser and a ScotchBrite pad.

PhotoSmith · Aug 12, 2007

Thanks everyone. I'll try the cleaner and ScotchBrite.

Many years ago (more than I like to remember) I worked in a commercial photography studio. Our lab manager used a chemical (not a commercial product) to clean mild rust spots on the SS processing equipment. He would use a different chemical to restore the SS after it had been cleaned. Unfortunately, my notes of what he used were lost a long time ago.

Kino · Aug 12, 2007

It was probably a very strong acid, followed by an alkaline to "passify" the stainless steel.

WD40 is a great cleaner/polish for parts that will NOT touch the photochemistry; use sparingly.

DaveOttawa · Aug 12, 2007

If you're feeling experimental you could try a citric acid stop bath (like Ilfostop) undiluted . The poster who said iron in contact with the SS will cause rusting is correct, the citric acid may remove the rust and at least somewhat passivate the stainless steel against further problems. Suggest remove the worst of it with scotchbrite first.
Citric acid shouldn't cause any other problems with stainless so nothing to lose by trying.
(I base this suggestion on the results I got cleaning up SS parts that had tarnished after exposure to ~350C in air using Alconox Citranox (google it if you want to know what it is), it removed the tarnish and to my surprise the tarnish did not reappear whne the parts went back into service suggesting some passivation had occurred.)

PhotoSmith said:
I have a few stainless steel sheet film hangers, and 8x10 SS processing tanks that have a bit of rust starting on them. What is the best way to clean them? Once they are cleaned do I need to do anything to the stainless steel to protect the effected areas?

Thanks.

c.d.ewen · Aug 12, 2007

For those unfamiliar with SS, it gets its stainless quality from a coating that forms on its surface. This is what is referred to above as passivation. Clean, dry stainless will passivate itself, unaided, in a week or two in a clean, dry environment. Drying after a rinseless acid wash will greatly reduce the time needed, depending on the acid used. In industrial settings, nitric is the acid of choice.

Get the rust off first. As Sam H points out, touching SS with any kind of mild steel embeds mild steel particles into the SS, causing rust. A good hardware store will have SS-wool. They'll also (in the USA) have a product called a 'Scrubbie', available in SS and copper. Green Scotchbrite pads are good, but red ones are better (scratchier). Look real hard and you'll find dark gray ones meant for SS.

Use Comet, if you have to, but rinse it well afterwards. Comet contains chlorine, which will cause pitting on SS surfaces. There are cleaners meant for SS: Zud and Barkeepers Friend are often available in hardware stores. These cleaners will contain oxalic acid. Acid good, chlorine bad.

Is the rust in cracks and corners? Try Naval Jelly, or an acid soak. Phosphoric acid is preferred, as it's not as nasty as nitric. I've seen it in hardware stores, but not very often. I suppose citric or even vinegar will work, too, but I've never used it. Warmer (120-150F) works faster than colder.

Unsubstantiated anecdotal knowledge: packaged beverages are made infection-resistant by making them acidic, usually with citric acid. I've been told that Coca-Cola uses a lot of phosphoric acid to achieve this effect. I've always meant to drop a rusty bolt into a glass of Coke and see what happens.

There's no need to put any kind of coating (WD40, wax, etc.) on SS. Clean, dry SS is happy SS.

Charley

Neanderman · Aug 12, 2007

Try Bar Keepers Friend. It contains oxalic acid and is compounded to remove rust on all surfaces and is non-scratching.

Ed

JHannon · Aug 12, 2007

I have an old Calumet 7' stainless steel sink bought used and has the original Care/Use sheet.

It has much of the same information given here and recommends an abrasive cleaner like Bon Ami to remove chemical stains. Care should be taken to rub with the grain on polished steel. No steel wool or steel brushes.

For more stubborn stains (corrosion or rust), they also recommend applying a 20% solution of nitric acid then rinsed with a 10% solution of baking soda to neutralize the acid, followed by a thorough flushing with water.

Free iron is stainless steel's worst enemy. Nails, iron filings, or iron pipe fittings should never be in contact. Use of water filtration is recommended in areas where the water has high iron oxide content.

I have the 1960's sheet if anyone needs a scan of it.

I wish I can say I am taking care of mine, it is in the garage until I get the darkroom finished, and I will probably be doing much of what the sheet says. (I don't see any rust on it though)

PhotoSmith · Aug 13, 2007

I'll give the citric acid a try.

Kino's guess about the acid followed an alkaline sounds right. I sure wish I still had my notes on those chemicals. I wrote it down because I knew it would come in handy someday. Who knew "someday" would be 25 years later!

Thanks everyone for your help.

PhotoSmith · Aug 13, 2007

Whoops. I missed the whole second page of recommendations above before my previous post.

This is great information and I will put it to good use.

Since these spots are small and do not look too bad I think I will try the Barkeeper's Friend with oxalic acid.

c.d.ewen's post mentioned the SS will passivate itself if left alone. Do you think this is sufficient, or should I do a 10% baking soda solution rinse like JHannon suggests?

Thanks.

Peter Williams · Aug 13, 2007

Neanderman said:
Try Bar Keepers Friend. It contains oxalic acid and is compounded to remove rust on all surfaces and is non-scratching.

Ed

This is what I use as well. Works great.

Samuel Hotton · Aug 13, 2007

Good evening PhotoSmith,
Yes, Bon Ami and a Scotchbrite pad will do wonders. Some of the rusty spots might have to be "Sanded" with an abrasive paper to get rid of the rust. If there is iron in the pits of the stainless, it will continue to rust. I've even had to scrape it out with the blade of a stainless steel knife. We did not use the oil of wintergreen on the inside of tanks that came into contact with film or chemistry. But we used it on the stainless sink surfaces and exterior surfaces of the 3.5 gallontanks in the sinks, my understanding was that it helped heal the natural skin that forms on stainless in contact with oxygen.
Sam H.

c.d.ewen · Aug 14, 2007

Use a new ScotchBrite pad, or at least an 'uncontaminated' one, i.e., don't clean your iron skillet with it then rub it on stainless. As Sam H says, you'll be embedding iron particles into the stainless if you do.

Bon Ami is a great mild abrasive cleaner, even for glass. As the package says, 'Hasn't scratched yet'. Zud and BarKeepers Friend's benefit is that they contain oxalic acid. BarKeepers Friend is a little more fun, as it foams. You can see where you've wiped. Zud seems to be a bit more abrasive.

I've never heard of the oil of wintergreen treatment, but each industry has its' own purposes.

The normal SS cleaning procedure in a dairy or brewery would be to apply a strong alkali, a caustic such as sodium hydroxide, at temperatures up to 180F to emulsify and saponify any organic material. Caustics don't rinse well, so this is followed by a mild acid rinse, often using phosphoric acid. To prevent mineral deposits, usually in the form of calcium (milkstone, beerstone), periodically a stronger, hot acid wash is used, generally using nitric acid. When new equipment is prepared for use, it is passivated by performing a much stronger hot nitric acid wash. The equipment is then allowed to air dry, with no rinse until just before it is used.

I wouldn't bother with a baking soda rinse, unless you're actually using a 20% nitric solution. I suspect that part of JHannon's procedure is done more to get rid of puddles of nitric acid that would eat through your plumbing. I don't know how it would benefit SS, but, then, there's lots I don't know.

Charley

ps: cleaning a lot of SS by hand will turn your hands black

PhotoSmith · Aug 15, 2007

Thanks again everyone. This has been very helpful.

alecj · Aug 23, 2007

Check with your local restaurant supply dealer. They have special cleaners which not only clean but leave protection after the gunk is gone. They know best how to take care of this stuff. I've used a liquid cleaner, thin, with a clean cloth, and it seems to leave a consistent sheen on the metal when it dries.

dario · Aug 27, 2007

Stainless is not stainless

I may be wrong, but I always understood that SS is only stainless in an oxidizing atmosphere. In a reducing atmosphere (e.g the presence of developer), it corrodes.

Dave Miller · Aug 27, 2007

I'm beginning to understand why I use plastic.

Alan9940 · Aug 27, 2007

I used a rather large Arkay SS sink for years in a environment with fairly high trace metals in the water supply (natural spring fed.) The water would etch the stainless, if I just left the sink to air dry, and, occasionally, I would get very small "cresents" of rust areas; I never really determined where the rust came from because I used filtration on all in-coming water.

That said, and before I really knew what was happening, I cleaned the sink with a dilution of phosphoric acid (use rubber gloves and good ventilation). I only had to do this extensive cleaning a couple of times; thereafter, I always squeegied the water out and dried with a bath towel. A little extra work, true, but I never had any issues using these steps.

Cleaning Stainless Steel?

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