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I often make jewelry from steel. I was curious about how rust effects the metal I use so I set up a little experiment. My theory was that the more a piece of metal is polished, the more rust resistant it will be.

I took a section of ½” galvanized pipe and chucked it in my lathe. I was testing 4 surface textures on the pipe.

Surface 1: Nothing done, left galvanized.
Surface 2: Scuffed down to 100 grit sand paper
Surface 3: Scuffed down to 400 grit sand paper
Surface 4: Polished to a mirror finish.

At first I dipped the pipe into water and removed it. I left it over night and checked it the next day. After 3 days It looked like nothing was happening.

I thought next to leave it submerged. I got zip lock bag, poured some water in, and dropped in the pipe. Three days later, nothing. I was surprised. I thought for sure this thing would rust.

Finally, I dropped a few other pieces of steel in to include a piece of galvanized wire, a section of 1” galvanized pipe, and a piece of 22 gage sheet metal. After another 3 days I emptied the bag and found out the following.

The galvanized pipe, regardless of removing the coating with any grit, did not rust. Though the pipe got a white cloudy residue on it. It appears the more the pipe was polished the less it got this cloudiness on it. This was same for both the 1” and ½” pipe.

The galvanized wire got the same cloudy coating on it. However, it rusted where there was no galvanized coating.

The 22 gage sheet metal rusted a lot. I thought about polishing a piece of it to a mirror finish and dropping it in water again but I figured this. Any piece of jewelry made with sheet metal, though most of it can be polished to a mirror finish, there will be some tiny areas that will not. So even the best polishing efforts wouldn’t make it water proof.

My conclusion is I'll be using more of the pipe from the electrical section of the hardware store.
As a machinist I'm sure you know, but galvanize is kind of toxic. I don't think it would be that good for jewelry that's constantly touching the wearer.
Hmmm... <br> <br>I've been playing around with steel lately, either dark annealed wire that I've been bending into calligraphy, or antique hardware from a cabinet I'm trying to restore. For both, I've been using linseed oil (not the boiled kind) to prevent rust. It's not perfect: it takes ages to dry, I have to be careful with the oily rags, and it can wear off. I've been thinking about trying lacquer or enamel, and have heard that Penetrol works. <br> <br>I'll be interested to see what else you encounter.
Very interesting experiment and equally interesting results. I would have guessed that when the zinc coating was removed, the material would rust, so I wonder if the &quot;hot dipped&quot; zinc process penetrates the steel (or iron) more than just coats? At any rate, the information is invaluable for making jewelry. Thanks for sharing!
in fact you are correct, hot dipped zinc coatings cause the two metals to alloy. the regular spray-on or electroplated coatings merely form a layer.<br>
Thanks for confirming my suspicions. ;)
a few things to take into consideration.<br><br>DO NOT use soldering or welding on that pipe.<br>Zinc fumes = BAD.<br>Cold join jewelry techniques only :-)<br><br>The reason the pipe didn't act just like the wire is... you didn't take off enough.<br>on most galvanized pipe, the protective layer is pretty darn thick.<br>there's the basic zinc coating on the surface, a layer of zinc/iron alloy, THEN the bare metal pipe.<br>It WILL rust, just takes a little longer. Also, adding salt into the equation will vastly speed things up. try this experiment again, adding a table spoon or two of salt to the water. I think you may be surprised :-) This will better emulate the effect of human skin, since our sweat is salty. So, pendants... probably OK. Rings? not so much.<br><br>Doing an oil/wax coating while the piece is warm(250-300 degree oven should be about right for most waxing) will be your best rust inhibitor.
We use this wax technique at work for fasteners with great results. I literally work on the beach and the salt air rusts everything.
Thanks for the good info.
Have you thought about &quot;Curing&quot; the steel the way cast iron is done? Good experiment.
Basically, what happened when you added all the pieces to the water at the same time was that you created a battery... Unless you use distilled water (A very poor conductor) most water available is either a bit salty (sodium being a metalic element by itself) or a bit acidic, which makes it a better conductor. That plus the two different metals equal Oxidation (the rust and cloudy grey zinc oxide) and a very mild electrical charge. Oddly, it is not the polishing itself, but the wax in the polishing compound that protects the metal by keeping away both oxygen and conductive substances like the salt and acid in your skin oils and sweat, but you're best off taking out the added insurance of a light waxing or clear coat. You also might find it interesting to look up how zinc is used as a sacrificial metal in marine setting to protect ships hulls and the like. Very fun experiment!
Very interesting and useful experiment, thanks for sharing.
Wanted to do this experiment but never had time..glad to see the results..Thanks for sharing.<br><br> By the way, the heart pendant i made last time started rusting about a week later. I removed it using sand paper, aluminium plated(wanted to keep the grey color) the pendant followed by 2000grit sand paper(not really required) and polishing compound. Works great and still has its mirror finish with no trace of rust(even months later)<br><br>Keep up with the great job. Awaiting more jewelry..

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