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Work Harden prefab hoop findings

Hi,

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! :frowning: :frowning: 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!!

Thanks, Deb H.

Planishing the catches should work harden them. You don’t need to smash them, just tap a bit and they will get a bit stiffer.

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:

2 Likes

Thanks Judy, I will planish today. Also thanks for your book, it was a big help on choosing the correct equipment and media.
Deb H

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 :smile: