A Rheological Misconception

Rheological item related to Wikipedia's list of common misconceptions

• Glass is not a high-viscosity liquid at room temperature: it is an amorphous solid, although it does have some chemical properties normally associated with liquids. Panes of stained glass windows often have thicker glass at the bottom than at the top, and this has been cited as an example of the slow flow of glass over centuries. However, this unevenness is due to the window manufacturing processes used in earlier eras, which produced glass panes that were unevenly thick at the time of their installation. Normally the thick end of glass would be installed at the bottom of the frame, but it is also common to find old windows where the thicker end has been installed to the sides or the top. In fact, the lead frames of the windows are less viscous than the panes, and if glass was indeed a slow moving liquid, the panes would warp at a higher degree.

Hat tip: xkcd

Accidental Discovery Files (#3)

While working on photosensitive glass, Dr. S. Donald Stokely accidentally overheated a sample.  The resulting product resisted breakage when dropped and could be used directly on the cooktop.  The material was called Pyroceram and was marketed as CorningWare.

Source: Wikipedia

Museum Exhibition of the Moment

On a recent vacation, we went to the Montreal Science Centre for the afternoon.  The exhibit on silicon-based glass in all its forms was interesting.  The only time that rheology reared its head in the exhibit was when glass was described as a solid liquid.
The videos attached to the website (in French with English subtitles) are excellent and cover mechanical resistance, electrical resistance, and thermal resistance.  I particularly enjoyed the mechanical resistance video, which compared an impact-resistant windshield to a peanut butter sandwich.
I did some work on inorganic glasses when I was a post-doc at the University of Texas at Austin.  One of the first things I learned was how unusual silicon-based glasses are, compared to other inorganic glasses.  In particular, they have a high melting point and do not dissolve in water.

Note: the Centre is also hosting an exhibit on human sexuality, which may trip Internet filters and is NSFW.

Video of the Moment: Rubbery Glass

Nanotech Glass Beads

According to Physorg.com, a "liquid glass" was invented in Turkey that utilizes nanotechnology.

The liquid glass spray (technically termed “SiO2 ultra-thin layering”) consists of almost pure silicon dioxide (silica, the normal compound in glass) extracted from quartz sand. Water or ethanol is added, depending on the type of surface to be coated. There are no additives, and the nano-scale glass coating bonds to the surface because of the quantum forces involved. According to the manufacturers, liquid glass has a long-lasting antibacterial effect because microbes landing on the surface cannot divide or replicate easily.

If this technology works as stated in the blurb, then the inventor has lovered the viscosity of the glass suspension by making the beads on the nanoscale.  This coating allows surfaces to be cleaned with hot water and has widespread applications.
Hat tip:  Andrew Sullivan's Daily Dish