technically an amphoteric P2O5 acts more as a glass-forming oxide
though not a substitute for silica.
- Present as
a trace element in some materials.
- Small amounts
give colloidal opacity e.g. chun glazes.
- Creates a
matrix of small bubbles in a glaze giving light dispersal particularly
pleasant in celedons.
- Shows as
a bluish flush in a glaze.
- Large amounts
give opacity, a dull surface, and blistering.
ashes - small amounts occur in these.
- Bone ash
- the most common controllable source. Also brings calcia.
Li.AlF.PO4 - also brings lithium oxide and
- superphosphate derived from phosphorite rocks.