Material World - When Glass Acts Like Concrete and Steel - NYTimes.com

Serious geekdom! - sm

Material World - When Glass Acts Like Concrete and Steel - NYTimes.com: "Cooled further and cut, pristine glass is very strong. But like a new car that plummets in value the moment it is driven off the lot, glass starts to lose its strength the instant it’s made. Tiny cracks begin to form through contact with other surfaces, or even with water vapor and carbon dioxide.

“If you take the freshly made surface and blow on it with your breath, you’ve reduced the strength of glass by a factor of two,” said Suresh Gulati, a mechanical engineer and self-described “strength man” who retired in 2000 after 33 years at Corning but still works for the company as a consultant.

Even one gas molecule can break a silicon-oxygen bond in glass, generating a defect, said Carlo G. Pantano, a professor of materials science at Pennsylvania State University. While glass is very strong in compression, tensile stresses will make these tiny fissures start to grow, bond by bond. “That’s what makes glass break,” Dr. Pantano said. “And if it doesn’t break, it weakens it.”"