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Shining Success... Glazing Techniques

By Mary Kay Hunt, CDT

alt 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