The two key characteristics of Glassomite that contribute to the range of benefits that
it offers are its glassy nature and its redox value.
The glassy nature of Glassomite means that it works a lot like cullet (recycled glass),
providing a range of glassmaking oxides to the melt, already in a glassy form so that
less energy is required to melt a Glassomite containing batch. For example, Glassomite
provides between 15 and 40% of the CaO in the new glass from batch, reducing the amount
of limestone and dolomite required. This reduces the energy required for the endothermic
decomposition of limestone and dolomite that occurs around 800-900°C. Glassomite is
glassy and liquid at glass melting temperatures, and therefore available to take part in
batch reactions at lower temperatures.
Glassomite is a reducing agent due to the presence of small amounts of carbon and sulphur
as sulphide. Due to the low levels of sulphide, it is a weak reducing agent when
compared to others that might be used. As a result, comparatively large amounts of
Glassomite are added to the recipe, resulting in more even distribution within the
batch. The interaction of Glassomite with sodium sulphate reduces the temperature at
which sodium sulphate decomposes, giving the beneficial effects of sodium sulphate
refining at lower temperatures.