K₂O₇Si₂Sn₂

Architectural potential

A tin-heavy potassium-silicate glass with a clear body at 500 MPa of compression and an unusually high 3.764 g/cm³ density for a soda-lime-family material — the tin content lifts the refractive index and the weight register toward lead-crystal territory without the lead itself. Natural placements are walked-on floor panels where refractive sparkle is part of the spatial argument, stair treads in civic and cultural interiors, pressed-glass column inserts in atrium architecture, transparent light-admitting pier elements in exhibition spaces. Against float glass the CO₂ balance is nearly neutral (-1.9%) but the energy reduction in the melt is sixty-two per cent, and the tin-potassium chemistry produces a body that behaves more like optical crystal in daylight: higher internal reflection, stronger edge-glow, a more emphatic coloration of the long-edge sighting. The potassium flux aids melt homogeneity at 1150 °C, and the 2.68 eV bandgap sits the body firmly in the transparent-to-visible register. Workshop batch reaches 5 kg and supply-chain score is 1.0. The caveat is cost: €9.10 per 400 g batch is an order of magnitude above standard soda-lime production, and the tin content shifts annealing schedules away from ordinary float practice — edge conditioning must be verified against the modified stress profile.

Material character

Clear, with a subtly warmer cast than ordinary float and noticeably more refractive bite at the cold-cut edge — the tin-potassium matrix throws a small but legible edge-glow that standard soda-lime stock does not. At 3.764 g/cm³ and 85×85×37 mm the slab is distinctly heavier than a soda-lime panel of equivalent footprint, a genuine two-hand lift, and the edge-tap carries a higher, longer ring than clear sheet glass. Surface reads pressed-glass matte with a shallow crown and one or two anneal striae near the long edges; edges cold-cut with the lapidary bloom that runs slightly coarser than float glass owing to the denser matrix.