Cutting Silver with a plasma cutter?

I happened to be talking to a jeweler who was working on a large piece
of 10 ga (about 1/8 inch) silver. She needed to make multiple closed
end slots, each around 6 to 9 inches long. She tried to use a jeweler's
saw, but it was extremely slow. She showed the piece to me, and asked
me how I would cut it. I immediately said plasma cutter. She is
probably going to come over to my shop to cut these slots.
Has anyone here ever cut silver with a plasma cutter? Anything I should
know? I asked on an art list I hang out on, and no one had ever done
it, although everyone seemed to think that it could be done. My
understanding is that plasma cutters will cut any metal, although the
speed of cut varies somewhat with the metal.
Richard
Reply to
Richard Ferguson
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Suggest you try a 'scrap' piece! - How are you going to attach GROUND ? Planning on using a copper screen ? - just an idea I thought of - wonder if it is good... Use a guide - but practice first with scrap of like material and a template then a small scrap to verify current and kerf! Air cool - Nitrogen might be better - less oxidation of the silver I would think.
I would think a nibbler would be better unless closed slots...
Martin
Reply to
lionslair at consolidated dot
It'll work fine. The only possible issue will be the fact that the kerf will be a bit tapered, as usual with a plasma cutter. I'm going to bet you'll be surprised at how fast it goes.
John
Reply to
JohnM
"lionslair at consolidated dot net"
snip-----
That's not an issue with silver. It doesn't readily oxidize, although the copper within sterling does.
Harold
Reply to
Harold and Susan Vordos
Considering inches per second with the plasma cutter vs. minutes per inch with a saw, I'd find it to be a bargain.
John
Reply to
JohnM
I'll bet you can tell me this; how does one tell the different silver alloys apart? Low tech method preferably..
The wife and I stopped at a yard sale, they had some old silverware for sale.. Some of the forks caught my eye for some reason, they looked different from the silverplate I'm familiar with- they were tarnished at the ends instead of all over, and it was a nice even black tarnish.. I asked the woman how much for one, bought it, took it to the car and cut a tine with my cutters and it was solid, not plated. I figured it'd be worth a small investment to get the rest, bought them for $3 and there was about 6 lbs. of those forks there. Put the ruined one under the torch and it was definitely silver (based on experience with silver solder). Some of the copper came out when melted, polish it and it's shiny again:-) Also, no smoke or boiling of the puddle so I figured they're not german silver.. Very fast heat transfer.. everything I could think of that would indicate silver was present. They're not marked sterling, whadaya think- coin silver?
Hated ruining the fork, but I knew of no other test on the spot.
John
Reply to
JohnM
Silver is generally marked as to content, but not always. Look for numbers, barring anything else. Coin would be 900, but several nations made silverware of even lower silver content, which I encountered as a refiner. I've seen silver marked as low as 720. That means, naturally, that the silver content is (or should be) 72%. It's still fairly good for color at that alloy, but it's obvious it's not sterling, which is 92.5%, which you likely know. As I recall, the lower silver content was common in Scandinavian countries.
You can test with Schwerter's solution, made up of potassium dichromate, distilled water and reagent grade nitric acid, but the test isn't real reliable, and difficult to use without you having used it for a long time, so you recognize and interpret the reaction. It's a super good test to determine the presence of silver, or not, but not great for determining percentages. I know of no easy test for that, unlike the scratch test for gold.
While I feel you may have silver, you also could find you do not. Cutting the tang as you did, if it's plated instead of solid, the action of shearing will often smear the pure silver (from plating) across the shorn area such that it will test silver, but some careful cleaning (filing) will usually disclose if there is white metal beneath the silver. To do that, test with a pure drop of nitric acid. If the are is silver plated, it will turn a creamy white color, but the notch you should file into the corner of any item being tested, and filed deep, will instantly turn green. The white metal is usually an alloy of either nickel or copper, each of which yield a green or blue solution. It's the fastest test to determine if an object is solid silver, or plated, assuming it is not marked. I always used this test in conjunction with the Schwerter's solution to remove doubt. Each take but seconds. If an item is worn well, it can be a non-destructive test. Anywhere the silver has worn away, Schwerter's won't turn blood red, which it does only with silver.
Having said all that, your heads up observations, particularly the rapid heat transfer, indicate you do have a silver alloy. We own several sets of sterling flatware. It's amazing how quickly the temperature of your food transmits to your hands. Very unlike plated flatware, and especially stainless flatware.
Marks are not always reliable. Many objects made in Mexico are marked silver, but are not. A lion is often used, or at least used to be used, in the UK to mark sterling, so look for that as well.
Harold
Reply to
Harold and Susan Vordos
Thank you for the information. For what it's worth, these say Albert Pick Co. on the shank. I looked 'em up and they made all kinds of stuff, from sterling to plate so that wasn't any help.
John
Reply to
JohnM
On an artist's forum, I asked the same question, no one had cut silver with a plasma cutter there either. However, somebody in the group got curious, and tried it on scrap silver. He reported that it worked fine, with a bit of dross. The group suggested cutting over water to save the silver from the kerf.
I have not tried it myself as of yet.
Richard
Richard Fergus> I happened to be talking to a jeweler who was working on a large piece
Reply to
Richard Ferguson

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