Archive | January, 2009

Choppin’ up some ponies

I wanted to pull something Sarah said from the comments section, since it is something that I’m mulling over right now.

(1) Could casting these small pieces “on the half-shell” (split up the median) then assembling them in greenware be doable/useful?

(2) Perhaps cutting problematic legs off, probably in the triceps area and biceps area (so they “lock” better) and casting as separate pieces might be the only way around it?

As many ceramic collectors already know, earthenware horses have historically been cast whole. This is how Hagen-Renaker made their horses, and then later how Joan did most of the production horses at Pour Horse.

But European bone china and porcelain have a different tradition, one where the horses are cast in pieces and reassembled. After Joan formed Marcherware with Mark Farmer of Alchemy, she began experimenting with assembled pieces. The process makes it possible to cast more complicated horses. Horses with twisty bodies and swirly hair bits – Sarah’s specialties! It also makes it possible to cast much larger horses than we’ve done before, because the individual molds are more managable. (A whole-body mold of a traditional-scale horse, when wet, is too heavy for most of us to lift.)

But this is all a rather new direction, and we’re still learning what might and might not work. Doing it on a small-scale horse like Vixen or Taboo is something that hasn’t been tried. We don’t know quite what to expect, or which approaches might work best.

So back to Sarah’s comments. These are the things that I have been pondering lately while making (properly soaped) production molds for Imp. Having clayed Vixen up (four times), it’s really clear to me that her extreme head turn is going to make whole-casting problematic. Her body just occupies so many different planes. I don’t think she will work without cutting her up somehow.

And I had thought about Sarah’s first suggestion, which is cutting her in half down the dorsal line. This is how the horses used by military figurines are made, though of course those are typically made from injection molded plastic. And I would need to exclude her neck and head, since it would be really hard to work in that area (to fuse the two halves) without damaging her face. I’m also not sure that it will help with her because bends so much.

What I think will work with her is removing her forehand. Or rather, removing her head, neck and left leg and shoulder. That way my fuse line falls predominantly to the chest and underside of the horse (where any shadows created by the fuse line might be less visible). And I can pour the piece through the big opening of the body.

Of course, I could get lucky a second time. Maybe she will work with just an inset piece over her turned head. I’m going to pour a number of rubber copies, because I think it’s going to take some experimenting to find what will work. But she looks like the kind of piece that might push the envelope a little, and that’s always good.

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A day in which I play Junior Scientist

Shortly after I met my husband, we both were given one of those Myers-Briggs personality tests. My test came back saying that I preferred “feeling” to “thinking”. In fact, I topped out the score in that particular category. It is no surprise, then, that I was never particularly attracted to engineering.

So it must amuse my husband that I now routinely come to him (a definite “thinker”) with engineering-type questions. I certainly have come to appreciate good problem-solving skills.

And that is what I needed for the problem with my inner pieces. I needed a way to seal the surface, and only the surface. I had already wondered if it might be better to spray some kind of sealant on them – something that dried almost immediately upon contact. My husband’s suggestion was that I find something with a wax base, since that not only would sit on the surface but could probably be removed with rubbing alcohol. He thought perhaps furniture wax might do the trick.

I decided to set up a test to see what might waterproof my plaster without soaking it through.

I didn’t want to wait for plaster to dry, so I used the backing off one of the bad Vixen rubbers. (I should note that here is where I made my first miscalculation. Well, make that plural. Did I mention that this post could also be entitled “How Lesli wasted a perfectly good day in the studio”? Anyway, the plaster should have been damp, not dry, because that’s how the plaster is when the mold is being made.)

All I had to do was sand off the keys and make it 1/4″ thick. As this picture shows, I made a rather big mess. But I got my thin slab of plaster to test.

Interestingly enough, thin plaster is surprisingly sturdy. It took several smacks with a metal hammer to get my test pieces.

And here are my candidate sealers; ScotchGard, furniture polish, matte varnish, dullcote, and wax resist. Off to the right is my control piece with my usual mold soap. I’ve etched a letter into the plaster chips so I know what’s what.

At this point, all I wanted to know was which of these actually sealed the plaster. As it turned out, plaster is really hard to seal. ScotchGard doesn’t seal it at all, no matter how much is applied. Surprisingly, neither did the DullCote, though the varnish did. Unfortunately the spray was strong enough that I suspected I’d never be able to use an insert to protect the design area from the spray. The only two “alternate” sealants that worked were the furniture polish and the wax resist. Of those two, the wax resist was both more effective and easier to apply, since it brushed on just like the mold soap.

Like I said, this is how I wasted a day in the studio. It probably wasn’t necessary, although it was certainly interesting. After calling Joan to discuss my results, it became clear that my real problem wasn’t that I was using mold soap, but that I was following the mold soap directions. (I tend to do this, much to my husband’s frustration.) The instructions called for 8 parts water to 1 part soap. So yes, Sarah, my soap was simply too wet.

I still plan to make a comparison test. I want to seal one Imp mold with my soap (straight, no water), one with wax resist, and one with Joan’s soap. I am pretty sure all three will work, but I want to know which one works better. And next time I’ll just wait for the time difference (Joan is on the other coast), and use my “phone a friend” option!

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