Question on testing antique eyeglass parts.

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borg

Member
Joined
Feb 24, 2008
Messages
22
Location
missouri
I recently picked up a lot of old gold-filled items. Included was bunch of parts of old eyeglasses, the middle parts that have the nose rests. A few are marked as 1/10 12k gf, but most aren't marked as to content. I found one full 'pince nez' frame that is marked 10k, so I decided to test the unmarked pieces. Every piece I test reads as 10k gold on my Mizar ET18 tester. (i know). I am filing so deep that I almost cut them in half, still says 10k. So I tried one of the marked 1/10 12k gf pieces, filed deep into it, it says it's 10k too. When I tried some other karat gold and gold filled, the tester read correctly. It's just these eyeglass parts. Any ideas??
 
borg said:
. Any ideas??
Yep! One of them is to not assume that the bridge of eye glasses is karat gold. Sure, some are, but they are few and far between. I can't imagine those without karat markings would be. It would be safe to conclude that I processed tens of thousands of eye glasses in my many years in the lab---found damned few karat gold bridges, and those I found were all ornamental, and 14K.

I have no knowledge of the unit you speak of, but a small amount of nitric acid can go a long ways towards dispelling anything you feel is true. Might not hurt for you to describe how you conduct your tests.

If you don't understand testing with nitric, it's time you opened Hoke's book and became informed.

Harold
 
Harold_V said:
borg said:
. Any ideas??
Yep! One of them is to not assume that the bridge of eye glasses is karat gold. Sure, some are, but they are few and far between. I can't imagine those without karat markings would be. It would be safe to conclude that I processed tens of thousands of eye glasses in my many years in the lab---found damned few karat gold bridges, and those I found were all ornamental, and 14K.

I have no knowledge of the unit you speak of, but a small amount of nitric acid can go a long ways towards dispelling anything you feel is true. Might not hurt for you to describe how you conduct your tests.

If you don't understand testing with nitric, it's time you opened Hoke's book and became informed.

Harold

Hello Harold. Actually, I didn't assume that they were karat gold. I found one full 10k gold frame in the lot and wondered if any other pieces may be karat gold as I haven't dealt with old eyeglasses much at all, but I know karat gold ones are out there. And because there are many old things made of unmarked karat gold, so I thought I'd see.

The tester I have is an electronic Mizar ET18 that I bought years ago. There is a test well on the machine where you mix an activator and electrolyte solution. You hold the item to be tested with an alligator clip wired to the tester and touch it to the solution in the test well to get your reading. These testers can be fooled by plating, which is why it is necessary to file a notch to test some pieces. Normally, when filing into an item past any plating, the tester will show it is not gold. With these pieces I filed halfway through or more and they still test as gold. ???

I do have the book too. :)

Thanks.
 
While I'm not privy to the exact base metal used in eye glasses (there's several), most of them will respond with a nitric test. Some may not. When I was actively refining, it was common place for me to remove some items from the remaining solids, of which bridges were a part. Most of them dissolve in nitric, but not all do. I accomplished this task after incinerating the recovered solids after a digest in dilute nitric acid. The remains were incinerated, then screened, with the obvious pieces of junk removed after visual examination. Doesn't take much effort once the base metals have been mostly eliminated.

It is my opinion that testing gold filled by the manner you've chosen isn't a good idea. If you're really interested in testing the unmarked pieces, you'd likely be best served by placing them in a small beaker and apply some dilute nitric. Heat the solution and allow the nitric time to work. If the base metal isn't dissolved by the nitric, prolonged heating will separate the gold filled layer from the base metal, what ever it may be. If any are karat gold, they'll remain intact.

If you subject 10K gold to heated dilute nitric, given a little time, it will allow the dissolution, at least on the surface, of the alloying material. The surface should turn a brown color (whether it's gold filled, or karat). If it's karat gold, you should be able to melt the piece with ease. If it is not, it most likely won't melt easily, and most likely will be built from a metal with a much higher melting temperature.

Because solid gold eye glass frames are not the norm,you can pretty much be assured that those that are karat gold will be so marked. The makers are pretty proud of them, and want you to know. Also, if the glasses in question are of recent origin, they may not be marked with the typical 1/1010KGF you may have seen (or 1/2010JGF, or even 1/1012KGF). After 1980, because gold has risen in value beyond reason, makers lowered the gold content. Some bear no more gold than if they were simply gold plated.

Harold
 
These were all old pieces with patent dates of 1894, 1907, etc. No new stuff. I think you are right about the testing, but I haven't yet acquired any chemicals or supplies. I've been too consumed with acquiring pm material to refine to actually do any refining. I think it's time to take the step. The process will let me know what is in each batch, so I can save time testing every little thing. Most everything I have hoarded is gold-filled and karat, so it should be pretty basic, and there's enough to keep me busy for quite a while. I have a few hundred pounds of boards and e-scrap too, but I think I'm going to pass them on to someone who knows more about processing them. Thanks for all your advice.
 
Hello when i was a kid we went to an optomistrist who worked from office back of his home. So 1960's. Solid gold frames were available then, cost a bit more but didn't break or more importa t, turn green on you. Titanium not around then. Gold frames easily available, then.

So you might find solid gold frames not marked such from that timeframe. The fake gold that didnot tarnish came out later.
 
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