Creation Porcelain: Establishing Proper Firing Programs

Underfired porcelain can contribute to a whole series of problems

	shades looking high in value or "too bright"
	lack of translucency
	lack of vitality or depth
	chipping or cracking during grinding
	bond failures (underfired opaque)
	excessive shrinkage

Before you begin, calibrate your furnace according to manufacturers instructions!

1	Program your furnace for a first dentin bake, according to the Creation firing chart .
2	Fire some dentin porcelain, either on a test crown or on platinum foil. Use your normal firing tray, and position the test porcelain at the same height in the muffle as your crowns will be (you can turn a firing tray upside down on it's pegs if you're using foil).
3	Compare the fired porcelain to the photograph on page II/19 of the Willi Geller Creation& Workbook. The porcelain should exhibit a slight shine.
4	If the porcelain appears granular or matte in finish, raise the high temperature of the cycle. Repeat the test firing. Do not change the hold time or the firing rate.
5	Once the correct "look" is obtained on the porcelain, program all other firing cycles on the chart into your furnace, adjusting the high temperature the same amount as determined for the first dentin. In other words, if the dentin firing was satisfactory at 940°C (20°C over the chart), fire the first opaque at 1000°C, the second dentin at 930°C, natural glaze at 950°C, etc.
6	Always fire the first opaque 20°C (35°F) higher for non-precious alloys. It has been established that this higher firing temperature can resolve frustrating cracking problems that sometimes plague users of non-precious alloys.

The following checks should help confirm your customized firing cycles.

Check #1

The first opaque should have a slight shine

Check #2

The second opaque should have a classic eggshell finish

Check #3

Self Glazing

Check #4

	You should have a satisfactory natural glaze with minimal hand polishing at 30 sec hold time.
	If you hand polish, use no hold time
	If 30 seconds hold is unsatisfactory, extend hold to one minute. If one minute hold leaves you with an inadequate glaze, you are probably still underfired.

Check #5

Creation porcelain is world renowned for its ability to match Vita shades. If your shades don't match easily, re-check your firing. Underfiring will cause lack of translucency, excessive value. Overfiring will cause lack of value and chroma.

Check #6

Grind on the fired porcelain. Underfired porcelain can chip and flake when you grind it.

Revision 0, 3/19/99