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twilightbanana

Telling apart different metals

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Sometimes I'll find myself not knowing which rings a certain bag contains.

Figuring out the size is easy enough with callipers. Most unplated metals can be identified by either colour or weight.

Brass: yellowish

Bronze: orange-ish

Copper: pink (when clean) or dark brown (when tarnished)

Aluminium: light weight (1/3 the weight of steel)

Titanium: light weight (1/2 the weight of steel). When in doubt between titanium and aluminium, try opening a ring. Titanium will fight back a lot more than aluminium.

A magnet and a small vinegar bath will help you identify different types of steel. Stainless steel won't be attracted strongly to a magnet, while mild and galvanized will.

If you're unsure whether a bag of rings is mild steel or galvanized, clean one ring thoroughly with soap and water to get rid of any grease, drop it into a vinegar bath and wait a few minutes. If it is galvanized, bubbles will appear on the surface of the ring.

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Another thing with Mild Steel is that there are two colors of rings in bags. In the fifteen or so pounds I've ordered, it's gone from just a dozen or so a pound to roughly a third of them: there are the nice ones with their dark oily coating still on them, but then there are also inevitably some without any sort of coating, a very, very light grey, and will probably be covered in rust already.

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Copper is much softer and easier to work. Might not be able to tell in the 20g range, but 16 and 14 you should be able to tell just by opening. Although that is more helpful if you have two bags and cant tell them apart. If they are mixed together, then good luck.

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I'd just let them sit for a few days. Copper will tarnish like copper and bronze will typically turn a nice deep brown. Like, you know, bronze. =P You could also use liver of sulfur and check that way. Or you could try opening/closing a few rings and get a feel for them.

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I have some fairly new copper and bronze rings that I can't tell apart. Any additional suggestions?

How sensitive is your multimeter? TRL uses C510 grade phosphor-bronze, which has a conductivity of 15% IACS. I use conductivity a lot for metal determination (it's a portable, non-destructive test), trouble is it doesn't work so well for small rings, the relative conductivity of each is fairly low.

You could melt them, too, but that probably wouldn't help much.

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Thanks, everyone, for the suggestions. Alas, the rings are all woven together into a Byzantine necklace my mother wears constantly. Even after a couple of months of constant wear the two metals look the same. I know it is a small section (about 5 inches), but it is a continuous necklace and I can't determine which section. I suppose it won't do any harm as the rings don't appear to be different and Mom is happy. After all, the goal was to make Mom happy for her 81st birthday. I think I'll leave well enough alone.

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