Wood glass?
An intriguing headline on a newly developed material, but the reality isn't quite so intriguing or new.

Engineers at the A. James Clark School of Engineering at the University of Maryland demonstrate in a new study that windows made of transparent wood could provide more even and consistent natural lighting and better energy efficiency than glass.

Transparent wood. Interesting. What's the advantage?

Transparent wood still has all the cell structures that comprised the original piece of wood. The wood is cut against the grain, so that the channels that drew water and nutrients up from the roots lie along the shortest dimension of the window. The new transparent wood uses theses natural channels in wood to guide the sunlight through the wood.

As the sun passes over a house with glass windows, the angle at which light shines through the glass changes as the sun moves. With windows or panels made of transparent wood instead of glass, as the sun moves across the sky, the channels in the wood direct the sunlight in the same way every time.

In other words, this isn't really wood. It's epoxy with the crosscut woodgrain used as internal deflectors.

Sounded familiar somehow.... Yup. I had already noted a similar bit of research done in 1901:

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From MIT tech journal in 1901. [Page 64 of the PDF.] The author, Charles Norton, got slightly carried away with his point:

We have so long given to window glass the task of keeping out the wind and rain, while letting the light and warmth of the sky enter, that the intrusting of another task to this universal detail of our structures is a step which interests the whole community. The window is henceforth to be not only an opening [for light], but a medium for sending the light in the direction in which it is most desired. Except where it is necessary to have [a view], conditions of economy will soon forbid the general use of plane glass. The age of plane glass has passed, to be succeeded by an age of scientific diffusion of light.

Can't you hear the grand fanfare? Cue the trumpets! The day of dull old flat glass is done! Boredom is shattered! From now on it's wine and roses and diffusing glass!!!! Wave of the future! Scientific! O glorious ripply prismatic morn! Huzzah! Huzzah!

Oops. Didn't happen.

Norton goes on to detail a series of experiments with various types of ribbed and prismatic glass, demonstrating nicely that diffusing glass gets plenty of light into the whole room, while plane glass lets the sun control the location. Sort of obvious, but the numbers are impressive.

What's truly striking is the near absence of any regard for artificial light. Gaslight was universal in 1901 and incandescent was spreading fast. Boston had its first incandescents in 1882. Norton mentions artificial light only once:

I have in mind a mill with two wings of a similar exposure. One is glazed with plane glass, the other with diffusing glasses, and on any cloudy afternoon you may find the plane glass wing all gaslight, while the other is amply lighted with diffused daylight.

I wonder if modern builders could pick up Norton's idea in a different part of the spectrum. In a passive solar design, would diffusing glass heat more of the house?


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Sounds like the current researchers are trying for coolness instead of heating, which is sort of pointless. If you want to avoid passive heating in the summer, you can shade the exterior with a mechanical blind or a deciduous shrub. No fancy materials needed. Let Nature regulate the shade.

Transparent wood also reminds me of the translucent wood that was used for hard-to-counterfeit scrip in 1933, functioning somewhat like a debit card.

Labels: scrip

  ¶ 5:45 AM