Condensation And Firing In Porcealin

Write a short note on the condensation of porcelain.
Or
Write a note on methods of porcelain condensation.
Answer:

The process of packing the powder particles together and removing the excess water is known as “condensation”.

Objectives of porcelain condensation:

To adapt the material to the requisite shape.
To remove as much water as possible. The more water is , removed, the less is the contraction.
To produce desired strong porcelain.

Condensation Techniques or Methods of Porcelain Condensation:

Condensation can be achieved by several methods:

Vibration:
- It consists of applying the wet porcelain to the platinum matrix and then vibrating the die in which the matrix rests.
- As the particles condense, the water rises to the surface.
- The excess water is then blottd with a clean tissue paper or an absorbent medium.
Speculation:
- The wet porcelain is applied with a spatula and then the surface is smoothened with the instrument.
- This will distribute the particle and cause them to become more closely packed.
- The water rises to the surface and it is removed with a lined cloth or blotting paper.
Brush technique or capillary action:
- It consists of adding paste to the matrix and dry powder is sprinkled onto the wet surfaces.
- The dry powder removes the excess water by capillary action from the mixture already applied.
- The particles move close together as the water is withdrawn.
Whipping:
- After the paste has been applied to the matrix, it may be whipped with a brush.
- The water is thus brought to the surface and it is removed.

Factors Affecting Condensation:

The success of condensation depends on the skills of the operator and the range of size of the particles.
If the particles are of the same size, 45% of a given volume will consist of voids.
If a number of particles are blended with larger ones, void or space is considerably reduced.
If three or more particle sizes are used that will achieve an even greater degree of compaction.
Powder consisting of mixtures of particle sizes compact more easily than those with particles of one size.
A well-compacted crown reduces firing shrinkage and shows regular contraction over the entire surface.
Thus maintaining the original form on a slightly reduced space.

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