17930091
Description
Mind Map by Alice Dolman, updated more than 1 year ago
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Created by Alice Dolman
about 5 years ago
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Briefly discuss two methods ofobtaining a
glaze on ceramicmaterials. Give the
advantages anddisadvantages of both
methods.
- Glazing can be done using an Overglaze powder mixed with Stain and Glaze Fluid and fired at the
same temperature as the 1st dentine firing (880⁰C) in air rather than firing in a vacuum, for 1 minute.
- Advantages-
- Uses a lower temperature which unlike self-glazing reduces
the risk of deformation/ pyroplastic flow.
- Uses a lower temperature which unlike self-glazing reduces
the risk of deformation/ pyroplastic flow.
- Disadvantages-
- Over glaze can enter perikymata/grooves carved into the tooth
filling them in and losing the aesthetical addition.
- if the glaze pools in certain areas it may lead to
discolouration.
- if the glaze pools in certain areas it may lead to
discolouration.
- Over glaze can enter perikymata/grooves carved into the tooth
filling them in and losing the aesthetical addition.
- Advantages-
- Alternatively glazing may also be completed without using an Overglaze, by firing the crowns in air
for 2 minutes at 880⁰C.
- Advantages-
- During the process the surface of the porcelain melts and
fuses just enough to fill in the slight surface irregularities or
porosities.
- During the process the surface of the porcelain melts and
fuses just enough to fill in the slight surface irregularities or
porosities.
- Disadvantage-
- This may cause the crowns to change shape and be
slightly rounded if kept at this temperature for too long
- If the porcelain is held at too high a temperature or
hold under heat for too long, the porcelain can slump
(undergo pyroplastic flow)
- the restoration can lose natural contours, recrystalise,
and become opaque(devitrify).
- the restoration can lose natural contours, recrystalise,
and become opaque(devitrify).
- If the porcelain is held at too high a temperature or
hold under heat for too long, the porcelain can slump
(undergo pyroplastic flow)
- This may cause the crowns to change shape and be
slightly rounded if kept at this temperature for too long
- Self-glaze is exposed to temperatures high enough to permit porcelain to fuse together and create a
smooth, glossy outer skin. It uses atmospheric pressure instead of vacuum.
- Advantages-
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