But, over the last few weeks, a number of us who work with and teach about Hadar’s Clays have been doing some explorations with the “Low Shrinkage Steel XT” product. Shown is a photo of a dozen pieces, which are about half of the ones I made during this exercise. While most of them turned out pretty much as I would have expected, there were a few surprises that I’m still trying to understand. I will likely have to make a few more pieces like the surprise-ones (when I find some more time to just explore), to see if the pattern repeats or if the surprises were nothing more than the occasional surprise.
Specifically, we’ve been looking at shrinkage. All metal clays shrink from when you first shape a piece in that medium to when it ends up as fully-sintered metal. Different products shrink different amounts. Some shrink more as they dry (go from wet clay to what we call greenware); others shrink more as they are fired (as the binder burns out and the atoms sinter (arrange themselves into a regular metal structure)).
Even working with just one product, different pieces will shrink different amounts in different directions. This leads to some interesting results, such as the fact that rings (usually) shrink smaller (though how much depends on the size and shape of the ring), the clay around cracks (usually) shrinks away from the opening (thus making it look larger after it’s been fired), and holes (usually) remain about the same size (depending on how big and what shape they are in relation to the clay around them).
With my background in mathematics and statistics, I tend to think of shrinkage as a “degrees of freedom” issue: if a clay wants to shrink a certain percentage and, for some reason, it can’t shrink that much in one direction, it compensates by shrinking more in the direction where it has more freedom to shrink. Except, it’s nowhere near as exact as that might make it sound…. It may vary from one time to the next. It may also vary from one artist to the next.
Why? Is it the amount of water in the clay? The humidity in the air? The altitude at which you work? The attitude with which you work? Phase of the moon? I could go on, but I think you get the idea: some variations are fairly clear while, for others, your guess is as good as mine! (Feel free to suggest additional ideas in the comments: I could use both solid suggestions and a few good laughs!)
But I write all this simply because I wanted to take a moment to say how much I enjoy exploring this entire “powder metallurgy” process: trying slight variations that go increasingly farther away from an original starting point just to see what happens. That is, in relation to the question in the title of this post (which I’ve been asked more times than I care to count) my answer is this: I hope to continue to learn as long as possible. I want to keep adding more information to my store of knowledge but, at the same time, I hope I’m never done learning!