April 29, 2008-
Durometer and Firing Issues:
The Craft Porcelain, an air dry product that gave me little confidence in what the dry hardness would be (durometer), was tested 2 weeks ago. A 3/8" ball was hardened over 24 hours. The result was a ver hard satin surface similar to acrylic nails, having some translucent properties. The product recommends hard glues such as super glue for attaching additional layers. It is amazingly hard, dense, maleable and has excellent translucence. Concerns are attaching additional layers
Tested Sculpey III brand polymer clay and blessedly purchased a Sculpey over thermometer. Our electric oven here in Colorado, as opposed to our gas one in California, has a very weak dial. The cooking temperature for sculpey is 275°F. The over wants to be either 225°F or 300°F. Grr. After much fiddling I fired 2 pieces and they scroched a little, but they were more for hardness testing as previous pieces in years past were a bit soft and doughy. These came out VERY hard if not a little toasty on the petal tips. It darkened the clay in an unappealing but subtle way. No Translucent was included in this mixutre (ivory only).
A third piece was done over 4 consecutive firings using ivory and translucent liquid polymer to assure adhesion of additions. This one came out without the darkening, however it is easy to see where the translucent medium was used vs the very opaque ivory. This piece was much longer and structural (right), the first layer being just the basic lathed outline of the handle as opposed to the more cap bead like structures on the first prototypes. Texture was kept much lower profile on the 3rd handle as lacy protruding petals were deemed a breaking hazard and uncomfortable for hours of handling the fan. This piece must be utilitarian first and foremost. Each additional layer added flowers, leaves and other more abstract decoration. Dry sanding to refine the base structure was done after the first firing. Because it was not wet sanded it is not shiny in thi sarea. As there is no detail on that section yet, it can be improved later.
The third handle also differed from the prototypes in that it was fired on the stick. The other two were formed with a foil barrier between the clay and stick and removed before firing to avoid damage to the wood. The third one was not formed with foil as it was deemed to not be particularly necessary. However, due to the almost triple length of the piece it had much more friction and could not be removed without damaging the shape. The others were removed easily but the foil and handling while off the stick enlarged the insertion hole unattractively. Firing did not affect the wood at all and the bond between the handle and wood seems firm and will require no additional adhesives. Likewise, the shape had to be fired horizontally, unlike the prototypes due to the 18" long stick. Happily, the form did not slump in the heat.
Below are the few pictures I have of the various pieces. Left, are versions 1 and 2 prototypes. Verion 2 is actually much more bulbous but the same lentgh as version 1, but foreshortening does not show this. Version 3, at right, is significantly longer than either of the previous two and includes so far, the base shape and 3 additional baked layers of detail. All of these pieces are ivory colored though photography appears to range from white and yellow to pink.
