Polishing steel

[Risu]

I'm working on a long term project right now that involves sheet steel. I've used the stuff before to make some Solo belt buckles, but I had to coat those in a thick clear coat and they still rust. For my current project, I really don't want to put anything on the metal because of it's decorative and classical nature. I'd also like to polish the steel to a nice bright reflective finish and I was hoping somebody here could tell me the best way to go about doing that, and if polishing the metal will stop the rusting. If not, is there anything I can treat it with that will stop it from rusting but not put an ugly coating on it?

 

[Replicant]

You would have to go with stainless steel if you want a rust free mirror polish without a clear sealer.

Sheet metal is galvanized-a thin zink coating is applied to the surface with electricity.

When you polish it you remove the zink and it will rust almost instantly.

I don't know why your project rusted through a clear coat.

 

[darth_myeek]

A buffing wheel from harbor freight will do the trick. I picked one up for a single job, and find uses for it weekly.

Stainless polishes nicely.


-DM

 

[Risu]

Is there any way of turning galvanized steel into stainless? That may be a stupid question. Failing that, where can I get stainless steel and if two pieces are welded together, will the welded area rust? What about the edges where I've used the grinder to take off the surface of the metal? Will those areas polish nicely? Also, if I get a polishing wheel will it wear down quickly? The grinding wheel I've got holds up really well, but the cutoff wheel wore down to nothing after one job. And do I need to coat the metal in some kind of polish before or after using that wheel? Sorry if some of these questions are stupid, I'm pretty new to this medium.

 

[Chiok]

Your rust after the clear coat would probably be due to the metal not being clean and dry before the clearcoat so the bare metal had some salty water from your fingers or the atmosphere before the clear coat went on. Clean and bare steel needs to be coated in oil to prevent rust and handle with gloves, I know I personally have fingerprints that will rust steel at a touch. When you're ready to paint or lacquer the metal, wash all the oil off, wipe down with meth or spirits and paint as soon as you can.

I don't think you can turn galvanised steel to stainless, and when working with galvanised, you need to be careful because the zinc coating is toxic and sticks to clothes and everything. I think welded areas will also rust if untreated.

With a polishing wheel or buffing wheel, they're soft furry things that you spread a bit of polishing compound on and buff your metal to a mirror shine. They don't wear down as such as they are only a means for applying polishing compound which has the micro abrasive particles that do the shining. Cutting wheels do wear down, no avoiding that, just don't stress the wheel with too much force or it'll wear down even faster and crack if you're unlucky.

Hope all that helps.

 

[Risu]

So if I weld together two pieces of stainless, I have no choice but to put a clear coat on the whole thing?

 

[Chiok]

I would believe so, yes, but I've never had to deal with it myself personally so couldn't say definitively I'm afraid.

Are you okay with welding stainless steel? Because it's not as straight-forward as regular steel if you want a good join. Internet is great to find out all the ins and outs, and if you've got the time and enthusiasm, just mess around with it.

 

[cheech9898]

You should be able to get it clear powdercoated at a local powdercoater if your wanting to do plain steel. Some of the 7xxx series aluminums tend to have a grain closer to steel when polished so you might look into that possibly. Otherwise you can just make the outer decorative buckle side out of polished stainless and epoxy that on top of the base buckle.

The issue with stainless is at welding temps, if air hits the weld pool... it oxidizes and leaves behind impurities in the weld that show/look like rust... it also cause the metal grain structure to change/crystalize from that of the original base and can cause strength issues. Best example is stainless exhaust systems for cars... you can tell the ones that were just quickly MIG'ed or TIG's up at a local exhaust shop vs a good aftermarket exhaust... the welds look bad in no time and usuallly fail in a few months from the heat cycling because they didn't keep an Argon gas flow or purge the inside the tube resulting in the back of the weld being crap & crystalized.

 

[Jumpin Jax]

You would have to go with stainless steel if you want a rust free mirror polish without a clear sealer.

It would have to be polished first, as raw stainless is matte finished, appears light gray straight from the shop.

 

[Risu]

Well, the project I'm working on now is actually a shield. It's a whole lot of surface area and I want it to look like a legitimate shield, not a fake. I can't use aluminum because from what I hear you can't get it in the right thickness or use a grinding wheel to cut it. And obviously it can't be welded. I wanted to make it out of a front piece and then side pieces for each side so that the metal would surround the wood and leather parts of the shield. The only way I could see aluminum working is as a casting, but I have absolutely no experience with that and probably don't have the resources.

What kinds of places carry stainless steel, particularly in large 2' x 2' sheets? The sheet metal shop I go to doesn't have any or know of any places that do.

 

[James Kenobi 1138]

Stainless Steel is steel with no iron. Unless you can remove the iron from galvanized steel (and add other metals for stregnth) your best bet is to start with stainless.

 

[Goodwolf]

Steel by it's very nature is mostly iron. Stainless has to have Chromium added. I'm no expert but I think it's a minimum of 10% or so to make it stainless.

 

[James Kenobi 1138]

More or less. Thge lack of Iron is why stainless is usually non-magnetic.

In metallurgy, stainless steel, also known as inox steel or inox, is defined as a steel alloy with a minimum of 11% chromium content by mass.[1] Stainless steel does not stain, corrode, or rust as easily as ordinary steel (it stains less), but it is not stain-proof.[2] It is also called corrosion-resistant steel or CRES when the alloy type and grade are not detailed, particularly in the aviation industry. There are different grades and surface finishes of stainless steel to suit the environment to which the material will be subjected in its lifetime. Common uses of stainless steel are cutlery and watch straps.
Stainless steel differs from carbon steel by the amount of chromium present. Carbon steel rusts when exposed to air and moisture. This iron oxide film is active and accelerates corrosion by forming more iron oxide. Stainless steels have sufficient amounts of chromium present so that a passive film of chromium oxide forms which prevents further surface corrosion and blocks corrosion from spreading into the metal's internal structure.

 

[Goodwolf]

Right, but if you follow your links to the original steel entry it says:

Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight (C:110–10Fe), depending on grade.

So there's iron in them thar... um sheets, but some Chromium as well.

 

[James Kenobi 1138]

More or less

 

[Goodwolf]

One of these days I'm gonna get around to learning about metalworking.

But at the moment I'm in the middle of teaching myself Japanese, Illustrator, and a 3d drawing application.

I'm swamped. /humperdink

 

[Replicant]

...when working with galvanised, you need to be careful because the zinc coating is toxic and sticks to clothes and everything. I think welded areas will also rust if untreated.

Handling galvanized sheet metal is harmless,while zinc is a heavy metal,the body requires a small amount.
The danger is in welding it.The fumes are toxic and nauseating,the cure is to just drink a glass of milk.

I am a Jounneyman sheetmetal worker Local 162.

More or less. Thge lack of Iron is why stainless is usually non-magnetic.

In metallurgy, stainless steel, also known as inox steel or inox, is defined as a steel alloy with a minimum of 11% chromium content by mass.[1] Stainless steel does not stain, corrode, or rust as easily as ordinary steel (it stains less), but it is not stain-proof.[2] It is also called corrosion-resistant steel or CRES when the alloy type and grade are not detailed, particularly in the aviation industry. There are different grades and surface finishes of stainless steel to suit the environment to which the material will be subjected in its lifetime. Common uses of stainless steel are cutlery and watch straps.
Stainless steel differs from carbon steel by the amount of chromium present. Carbon steel rusts when exposed to air and moisture. This iron oxide film is active and accelerates corrosion by forming more iron oxide. Stainless steels have sufficient amounts of chromium present so that a passive film of chromium oxide forms which prevents further surface corrosion and blocks corrosion from spreading into the metal's internal structure.

This is where swiss army knives get their name.....

1909 After the death of his mother, the company founder chooses her first name "Victoria" as the company name.

1921 Stainless steel is invented (also known as "inox"). The new brand name "Victorinox" is produced by combining "inox" with the name "Victoria".

 

[MDKronos]

There is no "more or less" about SS having iron in it. You CANNOT have steel without iron. There are only a few grades of SS that are non-magnetic. Welding SS does not have to cause oxidation especially if using a gas-shielded mig or tig setup. SS wire for both processes are available which will reduce or eliminate the occurance of rust/oxidation by-products.

If you are going to be working with metals often (which twice in a lifetime is often enough), it behooves you to pick up a book or two and taking a class at the local community college. There are so many different ways to work with metal (not just steel) to acheive what you are wanting to do, that you shouldn't let your inexperience overcomplicate the project.

Aluminium can be shaped using a belt grinder or belt sander. The key reason why you can't use a regular grinder is that the aluminum clogs the pores of the stone. There are no pores to clog on a grinding belt.

As far as finding sources for SS, you need to find another sheet metal supplier. Look in the phone book for surplus metals, commercial kitchen suppliers/manufacturers or scrap yards.

What kind of shield are you trying to replicate that requires being faced with metal?

 

[Risu]

As far as taking a class goes, I don't really have that option available to me. On my college campus we have metallurgy as a class, but you have to take several prerequisite art classes to be allowed to sign up for it, and I can't spend a whole semester taking classes I don't need just to take one class I want to.

The shield I'm making is Link's from Ocarina of Time. I've got everything figured out except for this steel issue.

 

[MDKronos]

As far as taking a class goes...
The shield I'm making is Link's from Ocarina of Time.

You don't need to take a metallurgy class, my post was intended to steer you away from some of the fiction that was posted earlier. There is truly nothing magical about working with metals, it just takes a little hands-on experience coupled with a very small amount of education on the various properties they exhibit.

Does this shield need to be functional or is it a static prop? There are awesome paints out there now that simulate various polished metals very realistically.

Polishing SS is a pain without power tools and proper polishing compounds. It is impossible to remove all scratches without practicing immaculate hygiene between polishing steps.