Nothing makes me grind my teeth more then opening my kiln only to find that the shoulder plate has warped all out of shape. There are several ways to fire shoulder plates that greatly improve the odds of ending up with a nice looking, symmetrical result. One way is to stack up a couple of posts that hold up your kiln shelf, pad with soft prop and set the shoulder plate on them. It needs to fit loosely enough to allow for the porcelain’s shrinkage and the porcelain and the posts can’t come into contact. This works pretty well with some sizes.
Larger pieces, however, need more support, especially if the shoulder plate is deep from front to back. A thin sheet of prop pressed lightly against the inside surface is usually enough support while held off the shelf by the padded posts. Again, remember that if the prop doesn’t give a bit to allow for shrinkage, the shoulder plate will split.
Smaller shoulder plates won’t fit over a square post, so you can use a triangular one, or roll a piece of prop to suspend it. Even small sizes will need a thin sheet of prop inside for support.
Another way to fire shoulder plates and large pieces is to pour a pancake of porcelain slip on the flat surface of a mold, let it dry, and slip it off. Lay this pancake on the Silica Sand or sheet prop on the kiln shelf, cover it with a fine layer of Silica Sand and place the large piece on it. The piece may still require some support inside to keep it from collapsing, but the pancake and the piece will shrink at the same rate so the piece doesn’t get hung up on and become distorted. The large Lady Grace head is a good example of a head that fires best on a pancake.
Dome heads, or heads that don’t have the top open, should be fired with the top of the head placed in a nest of prop to keep it from flattening. Silica Sand will also work. A half inch should be deep enough to balance it and keep its shape. If the sand or prop is too deep, it will keep the head from firing correctly.
I’ve had really good luck standing straight legs and arms straight up in the kiln. Sometimes I stand them on the foot down and put just ¼ inch or so of sand at the sides for extra balance, and sometimes I’ve put the foot up, which gives better balance. Only once have I had a foot droop when fired in this position. I put a little prop in the open end on the legs and arms to help them retain their shape, but it needs to be fairly loose.
Bent arms and legs can be a bit trickier. I usually tuck a little prop loosely in the open ends, place the opening down of the Silica Sand and support the rest of the limb with a mound of Silica Sand or soft prop. If the sand or prop is slightly rounded like the limb, it will support the shape, whereas if it’s flat, the piece may flatten somewhat as well.
You probably noticed that I referred to Silica Sand on my shelves. I used to use the sheet prop, but it soon becomes uneven and will cause the porcelain to hang up, so I’ve pretty much gone to sand on the shelves with prop for inside pieces. Being somewhat thrifty, I pulled pieces off the sheet prop to use for padding and support. One thing to keep in mind is that it’s a lot less pliable then regular prop. Lean a piece against a support of sheet prop, and the piece will flatten against it as often as not. It does work to tear in thin strips to place inside the head opening or to shape against the inside of a shoulder plate as long as it is loose enough. Don’t use one continuous strip inside the head or it will split the head. Use two or three pieces that will let one move over another where they meet, not butt up against other.
You’ll notice that the Silica Sand on your shelves will catch and hold small pieces of prop or maybe even small pieces of porcelain that dropped inside the doll parts when you were cleaning them, and then fell out on the shelf. These can fire to doll parts and ruin them, and the prop pieces can cause drag and distortion, so you need to run your sand through a loose sieve occasionally.
Leave about an inch between pieces in the kiln to prevent them touching as they first swell slightly, then shrink. This isn’t an issue in soft firing as they don’t get hot enough to stick together. Fire your cleaned and propped green ware to a cone 6, let it cool, and you’re ready to prepare to start the painting process.
Let me remind you again, before you start handling the prop, be sure to put on a mask so you don’t inhale any of the fibers. They can permanently damage your lungs!
