Contrary to the desire for strong mixing in
the melting zone and the sand grain dissolution process,
the fining process should be performed by a laminar
flowing melt, preferably with a shallow tank depth to
reduce the vertical trajectories that the bubbles have to
travel in order to escape eventually through the glass
melt surface. Here, in the fining section, the glass melt
should reach a temperature above the fining onset temperature
or the bubbles in the melt should start to grow
within a very short time to bubbles R > 0.5 mm by
bubble agglomeration or exposure to low pressure or
fast diffusing gases (helium, water vapor).