THERE ARE A FEW TRICKS that can be used to ensure
that the final glaze of a Creation restoration has
a beautiful, smooth luster. A properly glazed surface
is less likely to be penetrated by oral fluids, inhibits
the growth of plaque and duplicates the appearance
of natural dentition.
When you glaze, you have a choice of either using
glaze powder or self glazing. The Creation Porcelain
System includes its own glaze powder; there's a ten-gram
bottle in the basic Creation kit and two four-gram
bottles in the Make Up kit.
Surface Preparation
The surface condition of the bisque-baked porcelain
is an important factor in the success of the final
glaze. To produce a shiny surface that's uniform,
the porcelain must be completely abraded with a silicone
wheel prior to firing. If a rougher surface texture
is desired, do not use any abrasives prior to glaze
firing. Consider the quality of the abrasive when
finishing the surface of the porcelain. Some contaminants
could interfere with the quality of the final glaze
due to particles embedding in the surface. It's vital
that the case be thoroughly cleaned ultrasonically
in distilled water before you glaze in order to remove
finger oils and other contaminants that could influence
the quality of the glaze.
Using the Glaze Powder
When using Creation Glaze Powder, the high
temperature should be approximately 10°C or 18°F lower
than the first body bake. The consistency of properly
mixed Glaze Powder should be such that it "strings"
from the instrument during mixing.
Don't allow the Glaze Powder/liquid mixture to pool
on the restoration during application or loss of subtle
surface texture and discoloration may occur. A thin,
even layer of the mixture should be applied, and if
desired, appropriate Make Up stains placed next. And
remember always use Glaze Liquid with Glaze Powders.
Self Glazing
When self/natural glazing, the high temperature should
be no more than 20°C or 36°F higher than the first
body bake.
The texture of the porcelain surface before glazing
should be relatively smooth to promote an adequate
glaze at lower temperatures. It's important not to
over bake at this stage, for the lowest temperature
possible is desirable to prevent rounding of the sharp
incisal edges and loss of surface morphology.
Corrections During Glaze
If small additions to the contour are necessary, mix
15% glaze powder to 85% dentin or incisal using the
Glaze Liquid. Fire under vacuum. Use the high temperature
recommended for the self/natural glaze cycle.
Shoulder corrections can also be made during the
glaze cycle by mixing 30% Shoulder Powder to 70% Neck
Translucent (HT) with Shoulder Porcelain Liquid and
firing under vacuum as described above.
It's important that you don't let the porcelain dry
out while building or performing add-ons. Re-wetting
dried porcelain results in the creation of small air
bubbles between the unfired particles that will look
cloudy when baked.
The Firing Cycle for Glazing
Typically, there is no hold time when glazing Creation
but a 30-second to one-minute hold time may be needed.
Extending the hold time is preferable to raising the
temperature if the porcelain looks under-glazed. And
remember:
- The rate of climb during glazing should be 55°C
or 100°F per minute.
- If the porcelain is not glazed enough, try lowering
the heat rate to give the porcelain more time to
mature.
- A longer pre-dry time is recommended (two-minutes
minimum to six-minutes maximum) with all glazing
procedures.
- The vacuum levels must remain at 100% during the
body bakes and should be completely pulled by 650°C
or 1200°F.
Just a note
Many of our Creation users find that a porcelain
oven that pulls continuous vacuum rather than intermittent
vacuum will produce better results. Oven glazed porcelain
can be subsequently hand polished on a lathe using
diamond paste or extra fine grit pumice and a hard
compressed felt wheel. This technique will create
a more natural luster to the surface and instill variations
in the level of gloss which are more similar to nature.
For more information, please call your Jensen Account
Manager at 800-243-2000.
Revision 0, 3/19/99