All Pitted Out! (Or: Finishing The Finish On Fine Silver Ingots)

Hi!

Not having heard any answers from anyone in cyberspace, I decided to visit my jewelry supply store yesterday about 50 miles away.

The owner was a lifetime silversmith who now was one of the partners of the store. I was hoping that if I could show him the ingots, he could tell me how to fix my problem.

He weighed my results this far. He said that I had lost 20% of each of my ingots in the process of removing the patterns from each of the sides. I said I thought I had done worse, thicknesses as measured by calipers were at least only 0.70 inches. Patterns on one side went as deep as 0.015 inches on one side and 0.005 on the other. I grimaced at this, as I concluded with, “not bad for a first attempt!”.

He asked what equipment I was using. I told him a little bit about fly cutting and how it could remove layers between .001 inches and .005 inches. I also told him I had a Dremel available for polishing.

“We have some stuff you can use with your Dremel. Rubberized abrasive wheels. I’ll give you a coarse brown wheel for the pits, and a fine pink wheel for the scratches. 50 cents each, but they have hours worth of use in them.”

He also said that I was very close, but that I had to get my silver past the pits and scratches before I could even attempt to polish. “What are you going to do with them once you’ve polished them?”, he asked.

I said, “I would etch them with ferric nitrate, which I had read would be far safer to use than nitric acid”.

“Oh, and you’d use a resist marker on them. I see.”, he said.

He asked how I got the scratches in the first place. I told him about how after machining I was applying 12 steps of sandpaper grits from 60 all the way to 2000, but that some of the papers were putting in scratches in some places even as they removed the scratches in other places.

“That’s overkill”, he replied, “you only need 3 steps to polish silver. Start with 220 or bobbing compound, then either 400 or tripoli, and then use Zam. I’ll also sell you mandrels for the wheels.”

So I bought wheels and mandrels, and also bought 4 sterling plated 24 inch necklaces at $0.35 each for presenting my first pendants upon.

The next day I had a chance to experiment with my new materials, and some of the polishes I had bought a year in advance that were just waiting for this moment.

I actually have a mirror shine throughout the entire surface now. Pinhole marks and very fine lines remain, however, rather than the pits and scratches. These results are probably still laughable by the standards of a master. But perhaps these not so bad for a self-taught amateur who is going to give etched pendants away as presents.

Obverse sides of silver ingots after application of rubber polishing wheels, 2000 grit paper, and Zam

Reverse sides of silver ingots after application of rubber polishing wheels, 2000 grit paper, and Zam

Lessons Learned:

1) Stitched wheels last a LOT long on my Dremel than the cotton wheels for polishing.
2) The brown rubberized wheel removed some of the pits, tripoli worked on those pits which the brown wheel could not remove for some reason.
3) The pink wheel was good for sandpaper scratches.
4) Using the Zam after the wheels, I was still left with some white haze in places rather than a mirror shine.
5) I then applied 2000 grit sandpaper by hand to get a frosted surface.
6) Trying the Zam again, I was left with nearly no white haze, just a perfect mirror shine.

So here is my procedure this far:

1) Apply uphill oriented carbide fly cutter at 3000 RPM, using extra virgin olive oil as cutting fluid. NOTE: an engraving vise helps greatly to enforce a level cut, shimming the vise works even better.
2) Power sand to remove edge markings and to get center level with edges.
3) Remove pits and scratches by any means available such as rubberized abrasive wheels or Tripoli.
4) Prepare surface for Zam by frosting it with 2000 grit sandpaper, as applied by hand.
5) Use Zam to remove all of the frost, resulting in a mirror shine.

I’d still appreciate comments and critiques for how to do this any better!