rusty stainless....???

Yeah I know, it is called stainLESS steel. Otherwise they'd call it Does-not-rust Steel.

We polished out some hardware... you know, just to make it look "purdy"... it looked great for about two weeks but now it's got a light haze of rust on it.

Before it was dull and scratched but at least it wasn't rusty... and hadn't for thirty years.

The buffing wheel was new (so it wasn't contaminated with any other metal), the compound stick was new too....

Any clues as to what happened...?

 

Apparently the compound you used removed the protective film that was on the SS. Why this nicks and scratches didn't rust is beyond me. Could also be a change in the climate/conditions. Or perhaps thee was something in the compound that promoted the rust. I have been with the understanding that IF you're gonna polished bare metal and it is not intended to be a skid-free suface, like walls, desk tops, etc., wax it immediately after buffing. I know that when cleaning steel cookware you're to dry the surface immediatly then lightly coat the steel with cooking oil to retard rust formation.
Carl

 

Lew,

The steel was probably a low or cheap grade of stainless that wasn't passivated. The passivation process for stainless steels etches the surface and removes the iron particles that cause the rust to form. 316ss would be ideal but it's expensive and difficult to machine.

Mark T.

 

Well maybe this will help I am a boat builder and love my boats.
I have a vice that is forty+ years old, motorcycles ahhhhhh chrome and flames polished aluminum and stainless. Ok when you polish stainless it heats the metal and changes the molecular make up. Ya sorry to say it is not that tough,the surface rust is a dead give away but can be fixed.
www.englishcustompolish.com
look through the site and you will gain allot of info om metal polishing.
A complete misconception is that stainless steel is stain proof. It is not. It merely stains less.

Austinitic stainless steel won't tarnish, stain or discolor easily, but martinsitic will, and it all will if you overheat it or allow it to come into contact with steel.

All stainless also takes on bleed marks and stains from other metals easily .

Stainless Steel, Monel and Titanium are hard metals. You can forget many abrasives when working with these metals. Most of them just break down when confronted with these metals.

There is only one way to go.

Use an abrasive as tough as what you're up against. That means Stainless Steel abrasive compounds. These are compounds specifically designed to do the job.

One of the greatest risks when working with materials this tough is over heating. Over heating will not only warp your item, but if it is tempered you will break down the tempering and soften the surface. If your work piece is stainless steel you may cause it to release many of its oxides and carbon. Then it won't be stainless any more and will rust like ordinary steel. In the event that you encounter this problem wipe it over with a "Burn Paste", basically phosphoric acid. This is available from most metal working/welding supply outlets, which will reseal the wounded area. We then have to neutralize the acid by smothering it with sodium bicarbonate to prevent etching. You can of course do it our way with our electronic weld cleaner . This will dispense its own acid which doesn't need neutralizing, and will remove all signs of burn from welds on stainless.

If you have a finished product that you are trying to maintain a mirror finish on, at least 95% of hand polishes are a big no, no. Most of them will do no more than clean the surface at best, and at worst they will make it hazy by leaving light scratches in the finish. This is because they cut a little and loose their edge in rapid fashion.

The polish must have a serious abrasive to do anything. With most stainless, monel, etc, hand polishing is pretty much a waste of time. English Custom Polishing is one of the few manufactures of liquid polishes that will cut these metals, but be prepared for slow going.

If you are trying to do any more than clean up a mirror finish which is in good shape, forget it unless you have power tools. With a fabrication you cannot use abrasive compounds and buff wheels to remove machine or grain marks from manufacture as you can in aluminum or other softer metals. You have to cut with the correct tools. I like the nonwoven wheels, belts and discs. I don't like to bandy about trade names but sometimes one company has the product, Seco. They manufacture the finest bladder wheels and beltfiles in the world. When you have a large area, it's time to use belts for straight line stability.

Nonwoven belts and wheels will give you a reasonable finish, but still leave you a long way from that perfect mirror. The Seco tools are accompanied by a select range of belts, from 30 to 600 grit. It is important that at every stage you remove all signs of the previous cut, which will not always be easily visible. So we try to make each cut cross it's previous one at 90 degrees, this way we can see the scratches.

From here on in it will not be quite as easy to see the scratches as the finish comes up to your mirror.

Now it is time to buff wheel.

The first cut should be done with a good heavy stainless compound, and a good stiff buff wheel. At English Custom Polishing we find the pleated reinforced canvas is best as it carries plenty of abrasive, is stiff enough to put it down on the piece, and has a degree of flexibility for irregular shapes. The cut should be done in consistent straight lines of course and when finished will leave quite a nice, even mirror.

The next two stages should consist of a fine stainless abrasive and a finer chrome oxide. The fine stainless cut should be done with a pleated mill treated buff. These are still quite stiff and do an excellent job. The finest cut should be done with an untreated canvas buff. The medium and fine stainless compounds tend to vary in color, depending on the manufacturers dyes.

Each cut should, where ever possible, cross the previous one at 90 degrees. This will show up any marks left in from the previous cuts. Only when all marks are gone are we ready to proceed to the next cut. Once you are satisfied with your final stainless cuts it is time to move on to a good quality chromium oxide. Chromium is what gives stainless steel its brightness, so when we use a chrome oxide it is the perfect compliment and really brings your mirror up to an outstanding finish. Use a good quality linen buff for this operation. Now you should really have something worth looking at. The finishing touches are about to be done.

We do a final cut with a top quality calcined aluminate. These are superfine abrasives, which are quite hard, but very, very light cutters. That will do no more than remove very slight surface imperfections, and really bring the mirror to its ultimate lustre. This cut should be done with a very loose linen or cotton buff. If you like carnauba, here's your chance to use it to its full effect. Carnauba will not hurt these metals as long as it is removed every 12 months or so. Apply your carnauba, by hand. Make sure that not a single piece is uncovered and give it a few minutes to dry.

Once it has dried on the workpiece buff it off with a domet flannel buff. The more you buff the brighter it will get. I mean brighter! Call your friends, fire up the barbeque, pour out the beer and hand out the shades. You are now ready to show them you work!