# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DaGLgQgAwgW
- **Gondola URL:** https://gondola.cc/posts/67155475-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/5a4fcea271.jpg
- **Posted:** 2026-06-27T16:47:25.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Fused quartz is the only material that can comfortably hold a flame hot enough to make more fused quartz. That paradox sits at the heart of the oxyhydrogen burner, the quiet workhorse behind synthetic silica, optical fibre preforms, and the glassblower’s lampwork bench.

Quartz glass (amorphous SiO2) earns the job through a rare stack of properties:

- Softening point near 1660C, far above the 1085C melting point of the copper used in conventional torch tips
- Coefficient of thermal expansion around 0.55 ppm/K, roughly a sixth that of borosilicate and a sixteenth that of window glass, so the burner shrugs off the thermal shock of repeated ignition
- Transparency from deep UV through near IR, letting radiant heat pass through rather than soak into the nozzle
- Chemical inertness against the hydrogen chloride and silicon halides that corrode metal tips

The burner premixes hydrogen and oxygen at the tip through a set of concentric drawn-quartz tubes, producing a near-colourless flame around 2800C with no carbon, no sodium, and no soot to contaminate the work. That cleanliness is the whole point. In flame hydrolysis deposition the centre channel carries silicon tetrachloride vapour into the flame, where it reacts with the water produced by combustion:

SiCl4 + 2H2O -> SiO2 + 4HCl

The silica condenses as a fine white soot that grows, layer by layer, into a porous preform. Sinter it under vacuum and you have glass purer than anything pulled from the ground, the same trick J. Franklin Hyde patented at Corning in 1934 and the foundation of every long-haul optical fibre laid since. Dope the flame with germanium or fluorine and you tune the refractive index that guides the light.

The flame that ruins lesser materials is the same flame that forges the burner’s own kind.

#stemantics #materialscience #fusedquartz #glassscience #engineering

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## Tags

engineering, materialscience, fusedquartz, glassscience, stemantics

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