A newly cast ring still requires a lot of work before it is ready to wear. I began by carving a wax model, (see Part I) which I invested and cast (see Part II). Now I am ready to clean up the the ring. Since the last series of rings didn’t cast, as seen in Part II, I carved and cast new ones so I could show you finishing; how they go from a casting, still attached to a sprue tree to a finished, polished ring.
First things first, I need to get my ring off the sprue tree so I can clean it up. Once all my rings are off, I can reuse the sprue tree in another casting. To remove my rings I start by cutting them off the tree using sprue cutters, which are basically really tough wire cutters.
The rings that I am working on are sterling silver, but they are all black with oxides from casting. As a general rule, metal plus heat equals oxidation. To remove it, jewelers use a chemical bath called pickle to remove oxides and flux from their work. My preference is a dry pool chemical called pH down. It is available at most stores selling swimming pool supplies, even hardware stores have it. You can buy pickle specifically for jewelry, but I am pretty sure it’s the same thing.
Just add water to a few tablespoons of pH down in a warm crock pot and tadaa- it’s like magic! I just drop my pieces in and go find something else to do for a few minutes. When I get bored with facebook, my pieces are oxide free and now I am ready to move on to the next step.
Now that I can get a really good look at my rings, I inspect for any surface irregularities and file off anything I don’t want on my rings including where the sprue was attached. It’s very important to blend area where ring connected to the sprue into the natural curve of the ring. I also have some flashing that needs to come off, caused by a bit to much water in my investment.
For me, it’s most effective to just quickly knock these off with a file. When casting an object that requires a really fat sprue, I will break out the grinding wheels, but these are loud, messy, and generate heat quickly. File marks from a #2 cut file are also easier to get out then the marks left by grinding.
Once my rings are filed nicely where needed, I grab my trusty flexshaft and put a brown wheel on it. Brown wheels are my favorite polishing accessory. They take out my file marks easily and I can usually go straight to the buffer afterwards. Jewelers have to spend a lot of time removing marks left by files, sand paper, pliers, and so on. Anytime I can cut that list a little shorter and still have a beautiful finish I am happy.
Now that the entire surface of the ring is clean and consistent, it is time to visit the buffer for the final polish. To achieve the highest quality polish, I will go through two different rounds of polishing compounds on each surface of the ring. The last step is to wash off any remaining compound with dish soap, a splash of ammonia and warm water.
They only thing I hate about a highly polished silver ring, is trying to take a picture of it. Silver is very reflective, making it a photographers nightmare to capture the ring without unwanted reflections. Finger prints show up really easily as well.
You can actually see me taking the photo in this last image if you look at a large version. So annoying!
Anyway, this ring is finished! Once I complete the series, I will have rings from this collection available for sale in whole sizes 4 through 10.