One of my tasks this past week was to pour a new Finn mold. Finn was the first horse produced as a Blackberry Lane edition. He was also my first foray into molding a full-body horse. I didn’t make him alone; Joan made the rubber master while I watched and tried to absorb the process. I then brought the master home with me (much to the alarm of airport security in San Diego).
The training wheels were off, however, when it came time to make the plaster production molds. That’s the first one I made, pictured up there. It is more than a little inelegant.
As I showed with the step-by-steps on the Imp mold, sometimes the master mold isn’t a straight-forward representation of the plaster molds. For complex pieces (and we don’t seem to make any other kind!), it’s often necessary to make some of the interior pieces by hand. In the case of Finn, his ever-so-slightly turned head made it necessary to create a separate piece that covered the right side of his head and neck.
The trick with handmade pieces is that you have to envision how they work with the rest of the mold, and you have to do it on the fly because you are shaping the piece as the plaster dries. (You are also simultaneously trying not to get air pockets on the design surface and not spread too much plaster on the finished areas of the mold.) Needless to say, as the picture above shows, I did not get it quite right the first time. I ended up with an interior piece binding against another, which meant one edge fractured as I took the mold apart. Usually that just means you have some ugly flashing in one area of the casting (which works as a great reminder, every time you cast, of what you learned).
Unfortunately with this particular break, it also meant that when I poured the slip down the belly, it came right out through that little gap in the top. Of course, molds of new releases are never made except on a tight deadline, so it had to work anyway. You can see the staining where I have used blue and sometimes brown plasteline to plug the gap. It works, if more than a little imperfectly.
I made another mold a bit later, and it doesn’t leak. But it’s hardly much prettier.
It was interesting, then, to return to the master this past week with four years more experience. (Four years and a crash course on molding really difficult horses!) Of course, having a better sense of the word ‘undercut’ makes a world of difference. But there are little things, too, like not pouring the plaster too soon, or knowing just how much to jiggle the air bubbles out without shifting the rubber legs. As the picture shows, the 2010 mold is much cleaner. It also took a lot less effort.
I have been thinking about this kind of issue a lot lately. Those of us in the model horse community who work in ceramics have seen a marked increase in people wanting to learn various aspects of the medium. There really isn’t any getting around the fact that that almost every aspect – molding, casting, glazing – has a really steep learning curve. It’s made me think that to some extent, the most useful trait for someone taking up ceramics is just sheer stubborness.