Archive | Tools

A clever tool

I thought I would share some of the problem-solving that has gone into making Imp in ceramic. Each horse presents different production challenges. In the case of Imp, most of them have centered around his size. Just a few years ago, we thought stablemate-scale sculptures with thin legs were not feasible. That’s one of the reasons there are so many draft and pony breeds in ceramic; they have relatively thick legs. (Well, that and many of us working in ceramics are Anglophiles.)

We have gotten a lot better at dealing with thin legs, but problems remain with small horses. When earthenware horses are cast, liquid clay (slip) is poured into the mold, allowed to sit until a skin is formed, and then drained back out. As a result they are hollow inside, somewhat like a chocolate Easter bunny.

The goal is to get a fairly even thickness to this “skin”. Excess slip can’t stay inside the body of the horse or the barrel and hindquarters suck in during the drying period. Those larger areas must drain back through the pour hole. This means that the pour hole opening has to be large enough to drain the slip even after the skin has formed around the opening.

With most horses, this isn’t a big problem because they aren’t poured very thick. Imp is different in that he must be poured a little thicker, otherwise the area around his throatlatch closes off, leaving an air pocket inside his head. Air pockets that don’t vent to the outside can cause a piece to explode. The idea of opening a kiln to find a half-dozen Imps with their little heads popped off was really unappealing! The solution was to wait longer to drain him so the inner walls would be thick enough to make his head solid.

The problem with this was that his pour hole – the spot where the clay had to drain back out – was already too small. His belly just wasn’t wide enough to hold a proper sized pour hole. Walls thick enough to fill his head closed off his pour hole, but weren’t so thick that there wasn’t excess slip sloshing around in his belly. I needed to be able to clear the pour hole so it could drain.

Unfortunately just sticking something up inside doesn’t work well. It’s hard not to push through the pour hole and on into his back. Since the mold turns upside down to drain, the damage to his back would not refill. What I needed was a special tool just long enough to clear the pour hole, but too short to hit his back.

I needed something that could scoop the clay out of the opening, rather than just push it around, so I used my round-nosed pliers to make a loop from some armature wire.

Here I’ve used the rubber master to determine the length needed. I want the loop far enough inside that I’m not scraping it against the plaster mold. The metal wire is hard enough to chip the plaster. I want it just a little beyond the opening, but well away from the topline.

After marking the length I need with a Sharpie pen, I bent the remaining wire into a handle.

Then the handle was covered with polymer clay and baked. This stablized the handle and allowed me to hold it a little better. (The purple handle has also make it harder for me to lose the tool, which has made me wonder if I should paint all my tool handles bright colors!)

Since making the draining tool, I’ve been getting a higher percentage of Imps that survive to the bisque stage. Now my only production question is if I can get them to the final glazed stage.

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Airbrush issues

Like a lot of artists, I have a love-hate relationship with my airbrush. I always thought that using one was like having to rely on a brilliant, but decidedly temperamental, co-worker.

Things did get better, though, when I switched over to ceramics. Unlike acrylic paint ceramic underglaze remains water soluble forever, you don’t have to worry about dried paint clogging the inner workings of the airbrush. The downside is that underglazes are really abrasive, so over time you are effectively sandblasting the inner workings of the brush.

That means I got through piles and piles of these little needle cones. With each use the opening of the cone widens a little more, until the cone no longer holds the needle back enough to control the pigment. When I am painting consistently, I got through about a cone a month. After almost two years, the inside of the airbrush is toast and I have to replace the whole thing.

But the other problem I have had since switching to ceramics has been a sticky trigger mechanism. Since it is nearly impossible to salvage earthenware after it gets unexpectedly splattered, this has been a particularly distressing problem. The first time it happened and cleaning the brush did not help, I tried replacing the trigger. That didn’t help so I just replaced the brush. I wasn’t sure how the underglazes could be causing the trigger to malfunction, but the brush was near it’s end anyway.

This time, however, my brush was only a few months old and I just wasn’t keen to go buy another $85 piece of equipment without at least trying to find out why I was having this problem.

It turns out that the underglazes weren’t the culprit after all. This was – the small container of clear water that I use to clean the airbrush. I started doing this when I switched to ceramics. When I was done working I would take the brush apart (just like the picture at the top of this post) and dump all the parts into the water to soak while I cleaned up my workspace. Then I would dry the pieces and reassemble the brush. This wouldn’t have worked with the acrylics, but it seemed to do the trick for underglazes.

What I didn’t know was that this process was stripping the lubricants inside the brush. Most specifically, it was removing lubricant from the trigger mechanism. I didn’t need to replace the brush or even the trigger. I just needed to add some more lubricant.

This little tube was all I needed. Oddly enough, while I didn’t remember that you weren’t supposed to submerge the brush, I did remember that you were supposed to use special lubrication. That saved my not-really-ruined airbrush from being truly ruined by the WD-40 my husband wanted to try. (He is among those men who truly believe, down to the depths of their souls, that all life’s problems can be fixed with either duct tape or WD-40. Despite warnings on numerous airbrush forums, he remains skeptical that it would not have worked.)

Another interesting thing that I discovered through all this was that the underglazes abrade the needles themselves, as well as the cones. Both the cones in this picture are new, but the needle to the right has been in use for months. You can see it protrudes out significantly more than the needle on the left. The underglazes, with their clay content, have worn the metal enough that the needle is thinner. Now I know that even though the needles look fine (they don’t get bent like they do with acrylics), using an old needle is going to give me the same problem as using an older cone.

The good news is that not only am I a little wiser about the proper care of airbrushes, but I never did toss the last sticky-triggered brush. So now I have two working brushes.

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