Tips on polishing stainless steel and brass

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Hi, fellow metal artists. I am working on a coffee table design which will consist of stainless steel and brass and I am trying to improve my stainless steel polishing techniques.
I am still trying to get a mirror finish but scratching is a problem I am trying to overcome. I am not sure whether it is the abrasives or tools that I am using which is contributing to the problem.
I am starting the sanding process with 80 grit because of serious pitting on 8mm 316 S/S plate.

The process I use for polishing 316 stainless steel is as follows:
• Grit 80
• Grit 100
• Grit 120
• Grit 180
• Grit 240
• 3 stages of scotch bright
• 2 stages of cotton wheel and polish
(All Grit and Scotch bright stages are performed using a Stayer 7” variable speed rotating sander)

Q1.
I am interested in feedback from fellow artists who may have any advise to give on my polishing procedure.

I have no experience with working with brass, Although am keen to start working with it.

Q2.
I would like to know about polishing procedures for this material and how it compares to the Stainless steel polishing process.

The tarnished effect that brass rapidly obtains is a concern for an artist trying to achieve that polished look.

Q3.
Can this be overcome with a protective coating such as 2pack, acrylic lacquer or a wax coating of some sort??

All comments appreciated, please note I am in Australia and I may require further communication to appreciate some technical terminology differences.

Regards
Glen
Down under


Gene Olson's picture

Polishing anything

You are doing too much work and wasting paper and money.

When you go from rough to smooth the object is to get there as fast as possible. (unless you are really into penance)
The object is to even out the surface.

You grind down the high spots, that seems obvious.
Then you have scratches.

Get rid of scratches by sanding you need to sand with a finer grit until you reach the bottom of the scratch THEN STOP.

Now you have a new set of scratches to get rid of, and for those we need to use a finer grit.

The most efficient progression for stock removal is to double the grit each time.

If your deepest scratch is like something left by 24 grit paper, start with 40 grit.
Sand that scratch until your paper scratches a FINE line across the bottom of the offending scratch and
STOP
Take the 40 grit and apply a recognizable pattern, swirls, straight line, whatever. . .

Now split the grit size, go to 80 grit sand till the pattern left by the 40 grit goes away.
STOP
Now leave another simple pattern with the 80

now take a 160 grit sand off the the 80 pattern,
STOP make a new pattern

are we seeing a pattern here? 320, 1000 2000 rouge what have you

Gene Olson
Sculptor
Elk River, MN


eligius1427's picture

I have a question on this

I have a question on this subject as well. I am about to start a project in brass, a panel that has winding overlapping pieces, which need to be polished. Would it be better to fabricate the individual pieces, polish them, and tape them up before putting the panel together? Otherwise I'm not sure how I would get into the little nooks and crannies.

Jake


Bill Roberts's picture

I'd say the short answer is

Jake,
I'd say the short answer is yes. :)
And IF you order the brass pre polished..it'll save you even more time and effort. And it would come with a protective plastic. Then your just polishing any small areas that may have gotten "scuffed" in the forming and fabrication.
two cents,
bill


Bill Roberts's picture

I agree with everything Gene

Glen, I agree with everything Gene said.
But to start with "pitted" SS plate for a design that requires a polished finish......well it just seems like working "harder not smarter". I can think of better ways to "refine your polishing skills" LOL. I'm sure there's a reason you started with that material. So....I guess what I'm saying is if your design calls for a polished finish....I'd suggest starting with polished metal.

One thing that wasn't addressed in the polishing process was your "buffer". ALL your buffing wheels NEED to be isolated and protected from contamination. By that I mean, it should be in a separate "room or area" that isn't exposed to the the grit and grime of your fabrication area. And use different "wheels" for each abrasive compound. There is nothing worse than spending hours going through the stages of sanding only to find that the final polish has "somehow" left you with NEW scratches. A buffing wheel will only be good as the most abrasive compound that you've loaded it with. Meaning......you could take a rouge or final finish buffing wheel and put a more abrasive compound on it IF YOU HAD TO. But it would never be any good for the rouge or final finish polishing phase again. THIS does not work going the other way.....you would never try to use a wheel "loaded" with a coarse abrasive to then use with a rouge or final polish compound. I say this because sometimes you find yourself in a bind, for whatever reason, "needing" a buffing wheel and your unable to get a new one.

As a RULE once I designate a wheel for a specific abrasive compound....it's labeled or color coded and kept in separate ziplock bags or equivalent and not cross contaminated or exposed to shop grit or grime.

Sorry for getting so long winded...but I can't tell you how many times I've seen this happen.
Bill


Glen Jones's picture

polishing

Thanks Bill and Gene,
I appreciate the feedback, I can see as you say Gene I am waisting to mutch time and money. Bill it sounds like you guys have more options with material purchase in the states, in Australia you can buy polished SS plate but only up to 6mm thick. I like working with 8mm and can only buy standard mill finish.

I think I may be overdoing the polishing but using the corrct philosophy. Do you think the machine I am using is inapropriate?? Would a finer orbital sander work better, such as the type used on automotive panels?

Cheers
Glen
Down Under
www.deepsteeldesign.com


Rick Crawford's picture

Polishing

When I worked for the kitchen shop (made kitchens for hospitals and restaraunts, all stainless steel work), they used a flexible shaft with buffing wheels (the round pads that are stitched together with a hole in the middle) on the end to make a pad about 6" wide (or thick). This would be hooked to a motor on a portable table which could move around the shop. They had a separate one for each grade of rouge or polish they used.

Rick Crawford at Smoky Forge


Rich Waugh's picture

NO, an orbital sander is not

NO, an orbital sander is not the right tool for polishing. You need a real buffer, also called a buffing lathe. I'd suggest one at least one horsepower, capable of running 8" diameter buffing wheels.

You also need real buffing wheels if you're going to do serious buffing, particularly on stainless steel. Stainless is notably abrasion-resistant, which makes it hard to polish. So you need very aggressive buffing compound made especially for stainless steel, and you need a wheel that will hold plenty of compound. I like the hard Airway pleated wheels. Stitched muslin also works fine.

Brass is musch easier to polish than stainless, so you can get where you're going a lot quicker, and get a higher polish, too. With brass, after you finish with the sandpaper, you can to Tripoli, then White Diamond, then rouge and have a very high finish. On stainless steel, those buffing compounds will hardly cut the metal at all, so you need to start with emery, then go to a special stainless steel compound that contains microfine alumina abrasive.

If you need your buffer to be manipulated by hand, then you'll want to get a high-powered flexible shaft buffing head like aout body shops use. The kind that has a one HP motor on the floor or bench and a four foot flexible shaft to the wheel. These get a bit expensive compared to a stationary buffing lathe, but they allow you to work on pieces that are too large to handle on a stationary machine.


Gene Olson's picture

OTH on the other hand, if

OTH
on the other hand,
if you are still sanding

an orbital pattern will accent every darned scratch you missed.

while frustrating, this is good, no?

Gene Olson
Sculptor
Elk River, MN


Glen Jones's picture

polishing

Guys, how about protection from tarnishing after the brass has been polished. Any advice??

Cheers
Glen
Down Under
www.deepsteeldesign.com


visitor's picture

I have polished brass until

I have polished brass until my hair turned green. Lots of 316 C stainless also. My favorite tools are side grinders, a 4 1/2" and a 7", for initial grinding. I start with the roughest grit that will remove the impressions that need to be removed. This is not a process that can be farmed out to a laborer because you are changing the looks of the piece.
One piece of advice because I'm so cheap. Buy the best paper you can find. Don't try to use the Home Depot type discs. They are made for wood and soft materials. If you don't have a specialty store near you ask your local auto body shop where they buy their supplies. Otherwise you are limited to mail order from on line suppliers. http://www.klingspor.com/_vti_bin/shtml.dll/products/default.htm is one.
I disagree that random orbit sanders aren't useful. I find them especially useful in the higher grits for spotting where there are missed spots.
If you have an air compressor that will handle it a small air grinder with 2 or 3" discs will really speed your work. The main advantage is the ability to control speed. If you don't then finishing ready for polishing can be done with a Dremmel type tool.
Sorry for the long winded response but I'm willing to give more specific advice if you have questions during your progress.
Just what I do,
Lynn


Bill Roberts's picture

Glen,

Glen, there are two well known lacquers that are formulated specifically for "copper based" metals. Incralac and G.J.Nikolas. For the Nikolas: http://www.finish1.com/splash.htm

and for Incralac, made by StanChem

a google search will find tons of info.

bill

fwiw, I use Nikolas. But I've also had great results with the Incralac.


Glen Jones's picture

polishing

Thanks Guys, heaps of advice to keep me buisy for ages.

Cheers
Glen
Down Under