Saturday, December 19, 2015
it seemed like a good idea
Well, I guess it's back to work stuff. Almost four years ago a friend gave me a ball mill.
A ball mill, for those that don't know, is a device that turns glass chunks into powder. It consists of a heavy ceramic canister half filled with ceramic marbles that turns on the rods powered by the motor. The ceramic marbles spin and fall much like clothes in a dryer and this action crushes whatever material you put in the canister. Ceramists use them to powder and compound materials to make their own glazes. I thought I could use it to make frit (crushed glass about the consistency of coarse sand) from the chunks of lead crystal Gaffer glass that I have that I bought probably 10 years or longer ago.
The glass we use for our castings is Bullseye which is a soda lime glass. Soda lime glass is harder and stiffer than lead crystal. Lead crystal is softer and flows easier and at lower temperatures with shorter hold times. Casting at higher temperatures and with longer hold times can be tricky as the glass and mold material want to become one and then you get a scummy surface.
So, lesson over, all those years ago I bought a pound each of 15 different colors of Gaffer lead crystal which is a beautiful glass. It comes in frit and billets (thick slabs) for casting so I ordered mine in frit which is what I use to fill my molds. Unfortunately for me, their frit is not uniform in size and each bag contained glass from powder all the way up to big chunks. I sifted out all the fine particles of each color and used those to do a small smooth sided bowl and put the rest of the glass aside. Gaffer will only frit the glass to a consistent particle size if I order a minimum of 40 pounds per color. So ended my short foray into using Gaffer lead crystal for my pate de verre.
The other day I decided to pull out the ball mill and see if I could use it to frit the glass by stopping the process and sifting out the fine particles before they were turned to powder. I only use powdered glass sparingly in my castings because it makes the pieces come out more opaque.
Whoever had given the ball mill to my friend, who had it for years before he gave it to me, did not clean out the canisters before passing it on and there was residue caked on the sides, bottom, and thickly in the shoulders of the canisters and it was hard. as. a. rock!
It took me about 3 hours to scrape and dig and chisel that stuff out of one of the two canisters and that was after filling it with water and letting it soak overnight. Then I had to clean each and every marble because they also had whatever this white powder stuff is caked into the ridges of the marbles.
Finally I was ready to try out the ball mill. I selected a color that was in big chunks and one that I rarely use in case I totally screwed it up (or it gets contaminated) and set it to working. I figured I would give it 30 minutes or so and then stop it and see what I had.
What I had was a mixture of the big chunks...and powder. If I wanted to go to all the trouble to stop it every 20 minutes or so and sieve out the maybe 1/8 teaspoon of fine particles that might be mixed in there, then I might get enough fine frit to do nothing with.
So I'm just going to mill it all down to powder (since that's my only choice) and then do a piece or two with the powder and see what I get. Who knows? I may really like it.