Now that all pieces are cleaned and dry, they are ready to be fired in a high temperature kiln. The raw porcelain pieces are loaded into a very clean kiln on very clean kiln shelves. Items are spaced without over crowding to allow plenty of air movement around all pieces and an even temperature within the kiln avoiding the development of hot or cold spots.
Doll parts are propped and supported using heat resistant fiber, clean silica sand, or high temperature clay and wire props. The weight of all raw porcelain pieces must be supported to prevent warping.
Items must be placed to allow all air inside the hollow pieces to be safely vented to prevent an explosion caused by any trapped air breaking lose.
The kiln is set for the appropriate temperature for the type or brand of clay being baked. The kiln temperature is controlled either with an electronic monitoring device, a kiln sitter, or using an appropriate set of witness cones. The kiln is very slowly brought up to the extremely high temperature recommended by the slip manufacturer. Then the kiln is allowed to slowly cool down.
Aso Check out Seeleys tips on porcelain casting and firing.
If the correct temperature has been reached, then the clay will mature and vitrify into perfect porcelain. If the proper temperature has not been reached, then the “under fired” porcelain will look chalky. “Under fired” porcelain can be fixed by baking again to the correct temperature. Conversely, discoloration and warping will destroy all pieces in a too hot / “over fired” kiln.
All fired doll parts must be cleaned and scrubbed again! This time each piece is sanded with mild abrasive pads to remove any gritty residue. The resulting satin smooth doll pieces are ready to paint.
I fire my greenware to “.018” in the kiln sitter. “.019” is recommended, but the first is a little bit stronger. After firing, I soak my pieces in water, sometimes overnight, but at least 10-15 minutes before working on them. Soft fired pieces can also be glazed, as might be required for a China doll. In this case, soft fire to “.017”. Just be sure they are dry, before glazing them.
Cleaning greenware this way, the item is stronger, therefore less prone to breakage and scratching. The dust does not adhere to the piece, as is the tendency with regular cleaning. It also can be shipped, where regular greenware cannot.
I find it is easier to cut and bevel the eyes before I soft fire, but some of my students prefer to do this after firing. If it is done after firing, you almost have to use stone eye sizers rather than the wood.
To sand the soft fired ware, I either use a slightly worn #220 Grit Scrubber, but prefer the “Pink Sanders” that are available for sanding bisque. I cut them into 1/2″ strips, as it is easier to get into small places. You also will need stiff, flat brushes, as these help sand also. I like to finish up with the sponge side of the grit scrubber to smooth the piece off.
I also like to let them dry and check again to smooth any spots I might have missed.
Hope this helps those who have been asking how to clean soft fired pieces.