Tuesday, February 7, 2012

"Raku" in the Metal Studio

Sunday was Metal Studio day again - we have such fun playing on these days! I wish we could get together more often.

This time, we decided to tackle an enameling technique known as "Raku;" it bears some similarities to the raku pottery process, as I'll explain below.

I decided to use the process to create several pairs of fold-formed copper earrings. These start off with a large sheet of 24g copper, which I then cut into 1-inch squares.

Next comes the folding - each square is annealed, then placed in the vise and manhandled until folded, with multiple annealings in between each fold to keep the copper soft enough to work with.

Here is one pair of earrings after all the folds are placed and re-opened:
The dark dusky color is firescale from the multiple annealings.

The earrings were then pickled for a long time to remove the firescale;

The acidity of the pickle solution actually removes copper molecules while removing the firescale, leaving a matte finishe, so I then took steel wool to both sides of each earring to get a nice bright shiny surface again (although I certainly could have left them matte!) And this is the point where holes are placed for the earwires - don't forget to do this before firing!

The firing process is next - 2 firings with clear enamel to both sides was first, to get a good base coating.

Then comes the "raku" firing. These are the pieces, ready for firing (the raku color of enamel is in place):

That's my trusty Paragon kiln ramping up in the background - it has to get to around 1500 degrees before we can fire.

Now, more about the actual raku part of the process. Immediately upon removal from the hot hot kiln, the pieces must go into a container (with a lid!) containing shredded paper, so that they will ignite the paper and then smolder under the lid.

Here is the roasting pan we used, filled with shredded paper, ready for the emergence of the earrings from the kiln:

Isn't my nice clean roasting pan pretty?

So, the pieces are yanked from the kiln and unceremoniously dumped into the roasting pan, whereupon flames start shooting skyward (have the fire extinguisher nearby!!) I quickly clamped the lid on the pan, squelching all but a little of the escaping, acrid, stinky smoke, and ran for the door to get this smelly thing outdoors. OMG it stinks.

After about 70 minutes, the smoldering process ends and the roasting pan is cool to the touch, and we can continue.

Opening the lid:
The square burnt up thing is the screen that the trivets were on. Underneath there, buried in the paper, are the trivets and the earrings. And can you see that smoky yellow film on my pretty roasting pan?

My entire roasting pan is now coated in this horribly stinky sticky gunk. Several washings with baking soda and clorox (not together!) eventually removed it.

I fished out the trivets and earrings, and this is what I had:

You can sort of see some interesting, "oil-slick" coloration here, but really not much to look at, huh? Just square brown blobs, in my opinion. Then I started to think (which can be dangerous!) - if that nasty yellow slimy stuff is all over my roasting pan, it might just be on my earrings, too...

So I took the earrings to the sink and scrubbed them with dishwashing liquid, water, and an old toothbrush. And this is what was lurking underneath that film:

Now you can see the reds and blues and irridescent I normally associate with raku!


Each earring looks slightly different, but I could find 2 that closely resembled each other enough to pair them into 6 pairs. And the more I look at them, the more I love them!

This was time and labor intensive (and I had to clean that mess out of the roasting pan!); if I hadn't chosen to fold form the earrings it wouldn't have been nearly so time-consuming and difficult, but I really love the result!

Now the 12 earrings are piled on my work table, waiting for earwires. Sometimes the very last, finishing step (attaching a clasp, anyone?) is the one I procrastinate on. Well, that, plus it was almost 9 PM by the time we finished the firings, and I wasn't hanging around to place earwires - I wanted to go home by then!

2 comments:

Halinka said...

HI:-)
Very interesting technique and complexious processing,but the effects are incredibly astounding.
In a way,I had rather little knowledge about metal techniques,but thanks to Your blog it is getting wider.This is a very interesting blog post and I bet,the earrings are going to be fabulous.
Warm Greets-Halinka-

Cheryl said...

Wow, the raku finish is absolutely gorgeous! The fold-forming helps to give these pieces a more organic feel. I'm so looking forward to seeing the finished earrings....
Cheryl