Bristol glaze is a type of glaze used in ceramic ware.
It is known as a zinc-containing glaze.
The important constituent of Bristol glaze is:
\[
ZnO.
\]
Zinc oxide acts as a flux and also helps in improving glaze properties.
It can improve gloss, melting behavior, and surface finish of the glaze.
Tin oxide:
\[
SnO_2
\]
and zirconia:
\[
ZrO_2
\]
are generally used as opacifiers.
Antimony oxide:
\[
Sb_2O_3
\]
is also associated with opacifying effects in some ceramic systems.
But Bristol glaze is specifically associated with zinc oxide.
Therefore, Bristol glaze contains:
\[
ZnO.
\]