Some of you already know, I’m taking a class at the local college this fall (my first day in school in 37 years). The class is called “Creative Design in Metal” but most of the students are calling it a welding class.
Our first assignment was to make something out of two square feet of 18 gauge steel sheet (and nothing else) that is based on a pyramid shape theme.
After six days of thinking and coming up with nothing I wanted to try in steel for the first time...
So I'm in class today and the lady next to me pulls out three exquisitely designed cardboard cat sculptures. I suddenly felt very left brained.
The machinery in the class is very cool. Enviably cool. Can you imagine a disk cutter the size of a pizza? Or French shears that can go through 18 gauge metal like butter?
Anyway, after calling my son for a little refresher on how to apply the pythagorean theorem to find the height of one of my triangles, I was on my way and cut the pieces I needed to get started.
Next week we start welding (and I have to quit slipping and calling it soldering).
Experiment
Today’s experiment was putting fresh from the kiln pieces into a tumbler and tumbling like a usually do except with the addition of two pinches of citric acid. Hey, you never know. How do you think things are discovered?
Here are the pieces that are not polished or sanded or buffed or anything, just straight from the kiln (except for the piece that looks like a jumpring… that has been gone over with a radial disk). These are a mix of bronze and copper.
The ones with circles are the ones I put into the tumbler today for experiment #1.
This is what they looked like after two hours of tumbling.
This is what they looked like after five hours of tumbling.
My conclusions thus far? If something (particularly copper) has a smooth finish, it gets nicely shined up in the tumbler. The other things get shinier than they were, but even the subtlest of textures are still visible (which is probably a good thing).
Normally, those subtle textures (produced by my Teflon sheets during creation) disappear when I sand, but since I didn’t sand, they’re still there and merely getting shined up.
So I decided to take one of the little bronze disks out at the five-hour mark (that’s why it’s not in the photo) and polish it before continuing the tumbling… just to see the effect of tumbling on a sanded piece (we'll see that tomorrow).
Here are the pieces after 13 hours of tumbling.
Also, I'm not sure anything after 1-2 hours of tumbling makes a significant difference.
Citric acid has a pH of 2 (pretty acidic), but I don't think there was any reaction between it and my barrel. Also, the inside of my barrel doesn't feel tacky or sticky at all.
As you can see, even after 13 hours of tumbling the very subtle texture of my teflon sheet is still visible on the unsanded little bronze disk.
Today I'll clean my shot and run some more things through the tumbler.
Ooh, I've been playing with loading things straight in the tumbler - mainly because I am lazy and the brass brush hurts my thumb when trying to hold tiny pieces.
ReplyDeleteWhat was the citric acid supposed to do? Gentle pickling?
It works well for my copper pieces, but the bronze always seems to be more grainy and o needs some sanding first.
Yes, I also find it very hard to sand and polish small pieces.
ReplyDeleteI'm not quite sure I had an idea of what the citric acid would do. I was just thinking since it's a 2 on the pH scale, maybe it would do more of the wearing down of each piece.
Since I find that tumbling shines the metal up great but doesn't really do much as far as the same effect I get from sanding, I was hoping adding something acidic while tumbling might take care of that. But it didn't. :-)
And I have found the exact same thing you just mentioned. My copper seems to shine up so much better in the tumbler than my bronze.
In my next blog post, I'll show the difference between identical pieces when one has gotten a radial disk treatment prior to tumbling while the other didn't.
Thanks for your comment!