Describe a process of removing water from a porcelain mass prior to firing and explain why this is done.

Describe a process of removing water from a porcelain mass prior to firing and explain why this is done.

1. • Condensation is the process of packing the porcelain powder particles together and removing the liquid binder/ water.

2. • Condensing the porcelain reduces the gaps between the particles by driving off excess fluid, which helps increase the density of the final product.

3. • Methods of condensation if required include:

   • o Vibration
   • o Blotting with soft clean tissue
   • o After compressing whipping with a brush
   • o Sprinkling dry powder on the surface

4. • On firing, shrinkage of 15%-40% is possible. Adequate removal of excess fluid prior to firing will keep this to the minimum practicable.

5. • With modern feldspathic/aluminous porcelains little or no shrinkage occurs and simply removing excess fluid with a tissue is adequate. These modern powders should not be vibrated.

6. Removing water from a porcelain mass prior to firing:

   • • Improves contact between the metal framework and porcelain, this is because interfacial bubbles decrease and the bond strength increases.
   • • Decreases bubbles in the porcelain which increases translucency, aesthetics and strength of fired porcelain.
   • • Decreases the distance between porcelain particles which in turn reduces the porosity of the entire mass, increasing the strength and density of the porcelain.
   • • Prevents cracking and distortion through reduced firing shrinkage.