I have finished a series of hoops and have attached Rio’s hoop findings, item 695700. I then tumbled for 1 hour and thought they would be work hardened. Now that I am checking the fitting and alignment I have realized that the findings are still soft. When trying to do the “post type work hardening technique”, twist and pull with a modification, I broke one of the catch findings! As the catches, have a double curve, I obviously can’t pull them up straight and twist them to harden.
Any idea what I should try? I have already patinated and polished. Learning curve challenges!!
You are lucky to have learned early that tumbling does not work harden. So many people insist that it does and then sell earrings with bendy posts and wires. Technical investigation with a microscope strong enough to see the grain in a cross section of silver shows that only the outer surface is hardened.
Each year the Santa Fe Symposium presents scientific papers to the jewelry manufacturing community. I am providing a link to a paper that analyzed the nature of work hardening by mechanical burnishing by rotary tumbler.
They did their testing using 40 pounds of steel shot for 12 hours. They found surface hardening to a depth that was so small that it could be polished off. If not polished off, the added hardness would increase durability of the surface. They did not find the internal hardening similar to what we call “work hardening.”
At the end of the paper, these (condensed) conclusions were made: “Surface hardness is increased by both vibratory and rotary tumbling…final hand polishing may remove hardening imparted by rotary burnishing…the surface hardening imparted by tumble burnishing is not enough to resist deformation but may help with wear rates and superficial damage if it is not removed by final finishing processes.”
This link allows you to download the paper:
Thanks Vera, the study was very interesting. Of particular interest was that the rotary tumbler may have been a better choice to tumble these hoops as it hardens more than the vibratory tumbler. I am going to planish as Judy Hoch has suggested and then put them into the rotary tumble too.
Deb H.
Yaaay Vera!! I work with lots of “self-taught” folks who insist that tumbling is work hardening (on FINE silver no less) it is a myth that somehow got entrenched and I have been ranting and raving for years about the facts of work-hardening and annealing. I’m so sick and tired of crying in the wilderness
Well I gave up on the findings! I tried work hardening by burnishing first, then in the kiln. Burnishing after work hardening also failed. It seems that the findings are too flimsy. I measured them and compared them to some good quality hoops and they are .5mm verses .7mm on the hoops. I would not recommend the findings and won’t use them again. Mostly frustrated by the process as I tried it three times and wasted so much time. The earrings on the other hand look stunning! Any suggestion on another supplier of hoop findings? Stuller doesn’t carry sterling hoop findings.
Deb,
Please tell us how you tried to harden sterling silver using kiln.
Were you trying to age harden (heat harden) the silver items?
Almost all sterling silvers can be age hardened to significantly high hardness, higher than what you get from surface burnishing and/or tumbling.
Even extremely thin walled hoop earrings can be made significantly harder by age hardening.
Once I am completely done with a piece that needs to be hardened, I make sure that it is annealed and then I heat harden it in a kiln at 600 degrees for an hour. I recently rebuilt an old kiln and added a digital controller for just this purpose. I usually boric acid/alcohol coat first as the piece will have to be repolished a bit and recoating seems to cut back on the polishing. This process appears to harden it. Regarding Rio #695700, you should be able to solder the hinge and catch and then add the ear wire after you have finished the piece. Assuming that the wire is hardened, it should hold its shape. SS tumbling doesn’t harden the metal. It does produce some interesting finishes that I like. Good luck…Rob
Thanks Rob,
That is the procedure that I used. In the batch of 18 pieces, 3 of the catch finding broke when I attached the wire and then closed it. I could see that the closing catch was still moving and it was not secure. The wire didn’t have that “snap” so I opened and closed them numerous times. Two more finding broke, at the base on one of the sides. I then examined the balance of the findings and found cracks in the same place on 4 more pieces. I am meeting with my Goldsmith instructor tomorrow and will discuss this problem and then post her comments.
Deb
Hi,
I pulled the instructions from Rio’s website. Because I used easy solder, should have used medium! I dipped in boric acid & alcohol, and heated to 1330 for 60 mins, quenched in water. Then dipped again, and heated to 572 for 60 mins and allowed to air cool. Then back into the vibratory tumbler for polishing.
Deb
Hi Shan, the finding were stiffer but not as stiff as the hoops I had previously purchased. As I set them in position and then open and closed the hoop a few times they were still flexing and I couldn’t hear that snap when closing. Then when I examined under the loupe I found the hair line crack on the interior at the base of side of the flange.
To set them I closed them then tightened the closure with pliers at the top with the wire in place. Opened and the closure flexed out, repeating several times they still flexed the same amount.
I will wear a pair today and see if the stay on. And show them to my goldsmithing instructor this evening. I haven’t talked to Rio’s techs yet, I was building for a show, so just pulled the hoops out of production.
Thanks to all for the reminder of work hardening correctly, the things you forget when life takes you out of the traded for a decade!
Hi Rob,
I consider age hardening and heat hardening to be one and the same. I picked up the term heat hardening after starting to work in the jewelry industry! Age hardening is used in steel, aluminum and nickel industries. Essentially the metal is made to become harder by heat treatments. Normally no mechanical work is done on the metal.
To me work hardening is done purely by cold working the metal. Typically no heat treatment is used in achieving the harder metal.
I hope my reply is not too confusing.
Let me help understand why you asked the question.
Shan
I found a reference to age hardening on the Stuller site as the same as heat hardening. I had never heard the term age hardening other than in reference to that which results from a piece being manipulated while being worn. I learned something new, thanks…Rob
FWIW, the technical term for heat hardening, or age hardening, is “precipitation hardening.” Knowing this will help when you google for information on the process.
Of course, most of the articles on the process are for hardening industrial metals: aluminum, steel, etc.
I use both work hardening by burnishing and heat hardening. Yesterday when I wore a pair one fell off when I walked across the room. I then was flicking the closure with my finger nail and it moved.
The findings Rio 695700 are flimsy and must be for very small hoops. The closure is 0.38mm 27gauge and the wire 0.49mm 23 gauge. Rio’s website has the wire listed as 0.027 inches I measure 0.023 inches. I was surprised by how difficult it was to put on, customers with long finger nails would not be able to put these on. I don’t recommend these findings. First problem I have had with Rio in decades of purchasing from them.
In comparison to three pair of hoops I have; 1. 0.66mm wire, 0.72mm closure; 2. 0.53mm wire 0.54mm closure; 3. 0.73 wire 0.79mm closure.
Thanks for the refresher on work hardening, Ganoskin members are the best!
Deb
Rio Grande has come through with great customer service. I left a review on their website. They have since contacted me and offered for me to return the findings for a refund. I have been working with Rio Grande since 1997 and they always come through with great service!
Deb
A sort-of related question: I’m making hoops by soldering 21 gauge wire to the end of a casting and shaping the hoop. I twisted the wires close to the soldering point to work-harden it, but the whole wire is so long that I’m not able to twist the entire length of it. I also shaped and lightly hammered the wire against a mandrel, but only with rubber and rawhide mallets to keep the round-wire profile.
Then, of course, I dropped one and it easily de-formed, telling me I’m not doing enough. Does anyone have any special recommendations for work-hardening wires this long, and then shaping them?
