Apr 23 2011

Follow-up on Mokume-Gane with Copper and Silver

First – this is the last call for entries: my book Patterns of Color in Metal Clay: Canes, Gradients, Mokume-Gane, goes to the printer in about three weeks. If you have pieces that you would like to include, please hurry.

While mokume-gane literally means “wood grain metal,” when we say “mokume-gane design” we mean a much wider range of designs. Some of them I’ve shown in my blog posting Sterling Silver Clay, Copper Clay, and Mokume-Gane, and many of them will be introduced in my upcoming book. In the pieces shown in the next two photos, I’ve tried a design that looks like natural wood grain.

Both sintered at first firing, with no need to repeat the second phase. A project of mine about making wood grain design in copper, bronze, and Pearl Grey Steel is about to be published in one of the next issues of Jewelry Artist (Lapidary Journal).

Then I tried gradient surface, stripes, and mixed copper and silver.

The bird is made from pure copper clay. After the first firing it fell off and I had to re-attach it with paste. The paste was a mix of copper and silver, and so is the backing layer. The sun is made from a mix of equal amounts of copper and silver.

I was not so happy with the gradient part (the sky), so I made another attempt.

Both the sun and the bird came out very well attached to the background, but the copper part in them required repeating the second phase of firing. The gradient area sintered the first time.

These pieces bring to mind old sepia photos. It’s good to know that this option exists. Maybe when the price of silver becomes reasonable again we can practice it more widely. In the meantime, I am sticking to base metal clays, which are reasonably priced and allow a wider, richer range of color combinations.


Apr 18 2011

Bead Extruder

The tube adapter allows us to extrude tubes in different sizes and shapes, so we can make bails and hinges. There is one drawback to the commercial tube adapters that are designed for metal clay. We can extrude tubes only up to a certain size, although some of our discs have bigger holes.

For example: Here is the biggest square available in out set.

However, it is impossible to extrude a bead of this size. Here is why: When you place the disc on top of the holes you can see the 4 round holes of the tube adapter.

If you try to extrude with this combination of a hole and adapter, what will come out of the extruder is 4 snakes rather than a big square bead.

In order to extrude one tube or bead, the holes of the adapter should be invisible.

This, of course, is a much smaller square, and it will make a very small bead.

My thought was that if an adapter could be made with holes that were closer to its perimeter, it might be possible to extrude a larger bead. I tried a few designs, and so far this one seems to work best.

I made it from a brass sheet. You can try to make it from bronze clay, but I am not sure that metal clay is strong enough to withstand the pressure of the extrusion. This one bent while extruding. Also, it shouldn’t be too thick (over 4 cards), since that will make it impossible to screw on the cap of the extruder.

This adapter works with a screw mandrel.

t-06

Here is the adapter upside down, with the mandrel sticking upwards. A thin rubber O-ring is placed on the adapter to create some space between the adapter and the disc and to allow the flow of clay.

Here is the disc with the bigger square hole, laid on the adapter.

The holes are invisible, and it does work. Now all we need is someone to manufacture it for us.

An O-ring or a separate metal tube with the same diameter as the disc, separating the disc from the adapter, works better than the current commercial design of the adapter. After extruding, it is much easier to clean up.

Note: Since this information has been passed on to more than 200 people by publishing it on this blog, it is now considered public domain.


Apr 4 2011

Sterling Silver Clay, Copper Clay, and Mokume-Gane

After my blog postings about Sterling Silver using Quick-fire Copper and about Copper and Silver Mokume-gane, the next step for me was to play with making mokume-gane from sterling silver clay and Quick-fire copper. (See instructions for making sterling silver clay in my posting: Sterling Silver with Hadar’s Clay™ Quick-fire Copper. Here are some of my results. The first attempt is a pair of mirror-image earrings.

Before

Before

After

After

Before

Before

After (one side)

After (one side)

Other side

Other side

To my surprise, the lentil sintered without repeating the second phase of firing.

Here is an experiment with a gradient surface:

And Cabochons:

These are double-sided spinning earrings. They are small, but pretty thick. They also sintered without repeating the second phase.

One side

One side

Other side

Other side

This time I fired in both my kilns, front-loader muffle and top-loader fire brick. I used a ceramic cloth, which is the same as fiber blanket as far as temperatures are concerned. The firing schedule is exactly the same as for copper and White Bronze (how convenient – and weird!). In some cases I skipped the first phase by firing the pieces with a torch on top of the carbon. (I don’t recommend doing this with thin, flat pieces, since they tend to break, and I am not sure it can be done with White Bronze). When I didn’t skip the first phase, I fired in carbon for 30 minutes.

The temperatures for the second phase:

Top-loader brick: 1250°F/677°C;
Front-loader muffle: 1325°F/718°C.

I am going to repeat this schedule several times before updating my instruction manual (again?).

I did not find any difference between firing Quick-fire Copper with fine silver or with sterling silver. The metals seemed to fuse at the same temperatures.

I did find shrinkage issues with both fine and sterling silver. In some pieces that had a silver backing layer, the backing layer curved backwards because of greater shrinkage. This could be due to the brand of silver I was using. You can try silver clays with lower shrinkage rate. With the price of silver today, I am not sure I can afford it.

Advice: if you try, test first. Start at a low temperature, sand to check sintering, and if the piece has not fully sintered, repeat the second phase. If it still hasn’t sintered, gradually raise the temperature.

Warning: Do not fire silver and White Bronze in the same box. If you want to test them both in one firing, use two separate boxes.


Apr 2 2011

Copper and Silver Mokume-gane from Metal Clay

I didn’t think it was possible to make mokume-gane with a combination of copper and silver clay. I knew that the two metals won’t stick to each other, and if they do, they will alloy into a messy blob. I did try to make a gradient surface with copper and silver and ended up with sad results. But then someone asked me “Have you tried?”, and since then I couldn’t get the idea out of my head.

What if, I speculated, I fire at such a temperature where the two metals start to bond but not alloy yet? If this works, then it’s all about finding the correct temperature. (Whenever I ask my husband for his opinion on issues like this, he says: “firing schedule.”) The piece featured in this posting is my first attempt, no loss of silver whatsoever. Here is what I did:

I made the piece (see more information below).

I used a front-loader muffle kiln with a fiber blanket box. I fired the first phase on top of carbon: full speed to 1100°F/538°C, holding 10 minutes. To be safe, I fired inside carbon for 30 minutes. This is how it looked after the fires phase:

If I had made this piece with White Bronze (which I have done in the past), the White Bronze part would look almost as dark as the copper. You can see how white the silver areas are.

Then I started the second phase at the low temperature of 1200°F/650°C. Fired for 2 hours in carbon. I did not try to break the piece! Since the backing layer is copper, which is hard to sinter at this temperature, I sanded the back of it with 220-grit sandpaper. I saw some powdery areas.

I raised the temperature 20 degrees at a time. Each time I fired about 1:30 hours. The piece was fully sintered at 1320°F/716°C.

.

The mokume-gane part is treated with Baldwin’s Patina.

The question is: did the piece sinter because it was fired at the correct temperature, or because it was fired so many times?

When I fire mokume-gane with copper and White Bronze, I repeat the second phase of firing, to compensate for the low temperature. Surprisingly, in my front-loader, I fire White Bronze at exactly this temperature (1320°F/716°C). I am going to assume that what made it work is both temperature and repetition, so in my next attempt, I am going to use exactly the firing schedule that I use for copper and White Bronze (all firing schedules can be found in my instruction manual).

As for constructing this piece: regretfully, I cannot give instructions here for making this mokume-gane design and others because this is what I currently teach in my travel-teaching workshops, and it would be unfair to the people who pay to take these workshops. As far as I know, there are still a few spots available is my workshops in Dallas (with PMC Connection), TX; Brighton, MI and Saint Joseph, MI; and Rochester, NY (for details see my travel teaching schedule). There is also room in my Intensive classes at my studio. The rest of the workshops seem to be full.

Or, you can wait for my upcoming book, which includes more than 50 projects for different mokume-gane designs and techniques.

My thanks to Mary Ellin D’Agostino for her tips and suggestions.