Na₈O₄S₈Si₄

Architectural potential

This is the atlas's cleanest candidate for structural translucent glass at real architectural size. Five hundred megapascals of compression and a 100×100×48 mm slab at 2.078 g/cm³ — essentially standard soda-lime density — sit it squarely in the tectonic of walked-on glass floors, pressed-glass stair treads, column-like light-admitting piers, transparent landing panels, and floor panels inserted into mezzanine and atrium work. The sulfide flux modifies the melt behaviour without changing the structural register: this still reads as a soda-lime-silicate body in its bones, so annealing schedules and edge conditioning follow familiar float-glass tectonics. Natural placements are double-height gallery light wells, glass-floor thresholds between exhibition halls, transparent stair treads in public interiors, and pressed-glass beam inserts where steel-plus-glazing would otherwise be assembled as two separate systems. Against float glass the embodied CO₂ is almost identical (-1.9%), so the environmental case is neutral; the argument is the sixty-two-per-cent energy reduction in the melt itself, plus the structural-grade compression that opens walked-on applications float glass cannot safely address. Workshop batch reaches 5 kg, supply-chain score is 1.0, cost is €1.08 per 400 g — this is specifiable at real project scale. The caveat is the sulphide flux: melt-tank ventilation and annealing discipline must be rigorous, and large formats require careful edge conditioning against delayed fracture.

Material character

The slab reads clear with a barely perceptible warm cast from residual sulphur species in the melt — closer to clean float than to cullet-heavy glass. At 2.078 g/cm³ and 100×100×48 mm the panel sits with the familiar weight of a half-thickness architectural pane, a two-hand lift, and transmits a clean high ring on the edge-tap. Surface carries a low pressed-glass crown with faint anneal striae running parallel to the long edge, legible only against a light source. Edges cold-cut and cleanly polished, the usual lapidary bloom at the kerf. Against ordinary soda-lime float glass the tap is slightly deeper, the body marginally softer-looking under raking light — the signature of a sulphide-fluxed melt.