Second Bake

Problem / Question

After the second bake the second application separates from the first.

Cause (1)

The surface of the first bake was not appropriate.

Solution / Answer (1)

1. Lightly sandblast the first bake with alumina between applications.
2. Ultrasonically clean the first bake in alcohol or acetone between applications.

Cause (2)

There was insufficient dry-out time and/or too much condensing on the second bake.

Solution / Answer (2)

Leave the porcelain slightly wet and use at least 7 minutes dry-out time on all additional bakes.

Cause (3)

The High Temp on the second bake was not high enough.

Solution / Answer (3)

The temperature should be same as on the first bake.

Problem / Question

After the first bake the body has separated from the opaque layer.

Cause (1)

The High Temp on the second opaque bake is too high (the surface is too shiny).

Solution / Answer (1)

Lightly sandblast the opaque surface with alumina before application of body porcelain.

Cause (2)

The body porcelain was excessively condensed resulting in a gap between the body and opaque porcelain.

Solution / Answer (2)

Stop condensing as soon as the excess moisture is removed.

Problem / Question

There is metal black-line at the margin.

Cause

The opaque porcelain pulls away from the margin.

Solution / Answer

Apply the opaque porcelain all the way to the margin.

Before the second opaque application, wet the surface of the wash bake with water.