Column three, the network formers. This column contains the essence, the ur building material, the blocks, or in this case tetrahedra, of which the glaze is built. that which makes it all possible, its first element silica.
Column one, the network modifiers, or if you prefer, network busters, forming holes in the network, similar to runs in a stocking. This column contains the magic sauce, the bases which enable the glaze to melt and fuse at a temperature viable for pot and potter.
Column two, the amphoterics, the switch hitter, the play it either way components. We have met Alumina which is a network former, yet tightens the network, resulting in a more refractory also more viscous melt. This is essential for the potter, enables the glaze to melt without flowing off the pot.
Boron sits also in column two, it modifies the network without tearing holes in it as the network modifiers do. Boron can sit in the network as silica does, as a tetrahedron. The boron tetrahedra are slightly smaller than the silica tetrahedra. Alternatively, drum roll here, the boron can form triangles.
Boron, on its ownsies, can form a glass, with a lower melting temperature than any silica glass. This is a result of the flopyness inherent in stringing together planar triangles in space. Mixing some boron triangles into a silica melt, brings to the silica the flexibility of the boron glass. The result can be fusion at a slightly lower temperature. The network doesn't loose its connectivity however, so that glaze properties are altered without a change in maturing temperature. The effect is often seen as a smoother, more lusterous glaze which fits the body better, but matures at the same temperature.
As always, we show the boron tetrahedra as triangles in our two dimensional cartoons, the boron triangle are projected onto the plane as line segments, of the appropriate length, a bit shorter than the edges from the silica tetrahedra.
For reference we show silica and an alkali silicate glass. The remaining figures are of silica with tetrahedral boron, where the boron are shown as slightly smaller hatched triangles to distinguish them from the silica. Next is silica with the boron triangles projected onto lines, in its opening the network role. Last, a drawing of silica with boron (in its triangular form, shown here as edges) and alumina to show that the boron opens where the alumina tightens, balancing each other.
