# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DeUgWL-gpcR
- **Gondola URL:** https://gondola.cc/posts/71427935-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/fb4f6aa3b3.jpg
- **Posted:** 2026-10-10T16:24:50.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

Fibreglass begins as sand and ends as filaments thinner than a human hair, drawn from molten glass at speeds that rival a car on the motorway.

The batch is a carefully balanced oxide recipe. E-glass, the workhorse of the composites industry, is roughly:

- 52 to 56 percent silica (SiO2), the network former
- 12 to 16 percent alumina (Al2O3) for chemical durability
- 16 to 25 percent calcia (CaO) to lower melt viscosity
- 5 to 10 percent boron oxide (B2O3) as a flux and electrical insulator

Silica sand, limestone, kaolin clay and colemanite are fed into a gas-fired furnace operating near 1,400 to 1,550 °C, where they fuse into a homogeneous, bubble-free melt.

The critical step is fiberisation. Molten glass flows into a bushing, an electrically heated tray of platinum-rhodium alloy perforated with hundreds to several thousand precision nozzles. Platinum is chosen because almost nothing else survives prolonged contact with molten glass without contaminating it. Each nozzle releases a droplet that is mechanically attenuated by a high-speed winder, pulling continuous filaments of roughly 9 to 24 micrometres at speeds approaching 50 metres per second.

Rapid quenching freezes the glass into an amorphous state before crystals can form, preserving pristine tensile strengths above 3 GPa. A sizing is then applied: a thin aqueous coating of silane coupling agent, film former and lubricant that protects each filament from abrasion and chemically bonds it to the resin it will later reinforce.

Games Slayter at Owens-Illinois developed the continuous process in the early 1930s, and Owens-Corning was founded in 1938 to commercialise it.

Strength is not in the sand. It is in the speed of the pull.

#stemantics #materialsscience #composites #engineering #glassfibre

## Stats

- **Views:** 14,052
- **Likes:** 142
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- **Comments:** 8

## Tags

engineering, materialsscience, composites, stemantics, glassfibre

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