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Polishing a stainless steel sink?

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Bill Kahn

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#1
Well, I am a total beginner. So, figured I would post here. As I am not confident polishing a stainless steel sink is in the category of "Hobby Machining" please let me know where their are folks that puzzle about this sort of thing. Happy to go there instead.

My kitchen sink is a most well used part of the house. While I can clean it well, it still has a zillion micro scratches in it. I have tried to work on it with my 3" Griot Random Orbital sander (it is small enough to to get into the multiple concave corners) and using Black Carbon discs from http://www.onlineindustrialsupply.com/hook-and-loop-paper-discs.html. I like this as it comes in many grits, so I can start where I want and work all the way up to 2500 before polishing.

But the product wears out in about 20 seconds on the stainless steel. The finer grits even faster. I have tried the GoldStar, but that wears out even faster. And I have tried some 3M discs like 30260 Purple Clean Sanding Disc and that doesn't seem to do anything to the stainless steel.

Question 1: What sandpaper works best on stainless steel? Where can I get 3" hook and loop version of it? Do I use it wet?

Question 2: What is the best polish (or polish sequence) and best pad to get stainless steel gleaming? There are many many YouTube videos on this. I have tried a dozen polishes. Have not found anything that gets it great. Though some do pretty nice.

Question 3: What is a fair expectation for how hard it is to polish a stainless steel sink? Can one get it actually gleaning? Mirror like?

Of course, most happy to take this question to some other forum or even site. Surface finishes are a pretty specific niche of metal working.

Best, Bill
 

terrywerm

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#2
Bill, stainless steel can be tough to get to polish up, but with the right equipment it isn't too bad. I used to fabricate and machine liquid filling machine parts out of 316 stainless, and yes, it can be done. In the worst cases I started with a flap disc on an angle grinder to get the surface smoothed out a bit, then switched to abrasive discs.

I had the best luck with 3M Scotch Brite discs. On big projects I used them on an angle grinder, and on smaller projects I used the smaller 2" type that screw-lock onto a rubber backing pad/mandrel. I started with the coarse, then medium, then fine grades. This would bring a stainless surface to a fine enough finish that micro scratches were not large enough to "hide" bacteria from hot water washing and sanitizing of the equipment. Be aware that there are a number of different attachment methods for these small discs, types P, R, S and TN. They are not interchangeable so you will need to settle on one type and get a backup disk first.

Two years ago I made a set of stainless steel saddle bag supports for my son's Harley. They were built from 3/8" stainless rod which I first polished while chucked up in the lathe, then bent to shape and welded the various parts together. Afterwards I went back and polished the areas affected by the fabrication process. In addition to polishing with the Scotch Brite pads, I also used a cotton buffing wheel with various grades of rouge to bring the metal to a very high luster with a mirror finish. It took me two weekends to polish up the raw stock, bend and weld the various pieces, then re-polish as necessary to come up with the two brackets.

As for expectations on your sink, it can be made to shine like a mirror, but considering the abuse that a sink gets, I would prefer to stick with a finely brushed finish. A mirror polish will show every little scratch and nick. That mirror polish will take you quite a bit of time as well.
 

RJSakowski

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#3
I don't try to get a high polish on our sinks. A brushed or matte finish tends to hide the scratches better. I use the Scotch Brite pads. They are available in different grits. When they are new, they cut fairly well.

To get a high polish, I have used diamond paste, available from McMaster Carr, but not on anything as large as a sink.
 

Ulma Doctor

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#5
fine wet/dry sandpaper, Flitz metal polish , a wheel buffer from HF, a cordless/corded drill and the will to succeed is all that is needed
95% of the machines i work on are stainless, this is my cure for scratched up equipment
you can develop a mirror finish if you'd like
good luck!
 

jim18655

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#6
I was told once by a welder not to use any abrasive wheel/disk on stainless that was once used on plain steel. He said it would contaminate the stainless and make it rust. Any truth to that?
 

kd4gij

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#7
I was told once by a welder not to use any abrasive wheel/disk on stainless that was once used on plain steel. He said it would contaminate the stainless and make it rust. Any truth to that?

It does contaminate it and won't weld clean.
 

juiceclone

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#8
"most" stainless sinks come with what's called a "brush" finish. You can make brush finish stainless like new with about a 150 grit wet-or-dry paper or emery, wet, IF u stroke in/with the direction of the existing finish..very strictly.. Part of my job was doing this to food service equipment so it would pass as new. If you have already attacked it with all manner of abrasive devices, it can't be brought back to that. Kinda attack with abrasive pads and see what suits u.
 
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