Medieval churches with stained glass were photocatalytic air purifiers with nanostructured gold catalyst. Yep. They were.

For your Just Too Cool file… a reader alerted me to a post at Daniel Mitsui’s blog.

This, if true, really is just too cool:


Information Week:

The glaziers who created gold-painted stained glass windows for mediaeval churches in Europe… developed a solar-powered nanotech air-purification system.

According to Zhu Huai Yong, an associate professor at Queensland University of Technology in Australia, the gold paint used in mediaeval-era stained glass windows purified the air when heated by sunlight.

For centuries people appreciated only the beautiful works of art, and long life of the colors, but little did they realize that these works of art are also, in modern language, photocatalytic air purifier with nanostructured gold catalyst, said Zhu in a statement.  [I knew it! Well… not really.]

Zhu said that tiny gold particles found in mediaeval gold paint react with sunlight to destroy air-borne pollutants like volatile organic chemicals/compounds, which are emitted from paints, lacquers, and glues, among other things.

These VOCs create that new smell as they are slowly released from walls and furniture, but they, along with methanol and carbon monoxide, are not good for your health, even in small amounts, Zhu said. [Note to self…avoid new car smell…]

When interacting with gold particles, sunlight creates an electromagnetic field that reacts with the oscillating electrons in the gold. This field resonates and breaks apart pollutants in the air, according to Zhu. The byproduct is small amounts of carbon dioxide, which is better than carbon monoxide in terms of human health.

Zhou expects his research will help make the production of chemicals at room temperature more cost effective and environmentally friendly.

More gold-painted stained glass NOW!

It’s the green thing to do.

About Fr. John Zuhlsdorf

Fr. Z is the guy who runs this blog. o{]:¬)
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  1. NBW says:

    Very Cool! I think the medieval people knew more with less technology.

  2. Johnno says:

    I say we take the Social Justice Collection money and put them towards this initiative! Clean air matters! If you’re not for it then you reject Vatican II and don’t care about the poor women… or something…

  3. APX says:

    Very Cool! I think the medieval people knew more with less technology.
    I find this amazing considering my home diocese spent hundreds of thousands of dollars on solar stained glass windows that were apparently supposed to be the cat’s meow, only to have the majority of them mysteriously crack and break shortly after the Cathedral opened. Deo gratias for insurance, but I think we should go back to medieval engineering. It seems to have a longer life span.

  4. Don’t avoid the new car smell! Just paint your car windows gold!

  5. NBW says:

    Sorry to hear that happened. Did they ever find out what caused the cracking? I also wish we could go back to medieval engineering; and add medieval art to that as well!

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  7. Imrahil says:

    I doubt we can say they had less technology in the Middle Ages. We are not speaking about the Stone Age, but about the age of the Chartres Cathedral.

    They had, obviously, a less progressed technology (note: in technology there is such a thing as progress). Their technology was 800 to 1000 years behind our times; what a surprise… They did not have some inventions we find quite useful. But they used a lot of technology to get around these lacks. (I’m not speaking about such inventions as really changed the culture: the letter-press, the combustion engine, or our digital age which in a sense starts with the telegraph.)

  8. PA mom says:

    Thank you for this, I can bring it to class where we have just started the Medieval times in Church history.
    There was a book called Cathedral which I saw once. Pencil drawings with the various steps of building a cathedral, with a little fictional story to go along. It is amazing how they could accomplish these things. So slowly, to be sure, but so beautifully and solidly as well. It should be of no surprise that God did all He could to help His people’s health, including inspiring engineering which cleans the air. After all, He loves us.

  9. Widukind says:

    I remember reading somewhere that in medieval times the sick were taken into the churches and and as an aid to their healing were laid in the sunlight that came through the stained glass windows.
    This might have to do with the color of the light though.

  10. The Masked Chicken says:

    The photoactivity of gold nanoparticles has been known since the late 1990s. Gold nanoparticles are currently a hot topic in cancer research, because it is possible to infuse anti-carcinogenic compounds into the nanoparticles, inject them into a tumor site, activate the gold particles with a laser, rupturing the particles and releasing the compounds.

    Gold nanoparticles, especially in combination with cerium, zirconium, titanium, and aluminum oxides, have reductive abilities when photoactivated. They can reduce ketones (responsible for the “new car smell,”) to alcohols, etc.

    The photocatalytic process described in the articles is entirely an accident. Gold was the kingly metal and used in stained glass. It would, also, only reduce the volatile compounds that could find their way to the window, so the reduction was not all that much. Sunlight coming through the windows during the summer would probably have been just as effective on a larger scale, since it penetrated the entire Church, although the processes would have been different. Photoactivated gold acts catalytically, whereas straight sunlight acts thermochemically.

    The Chicken

  11. Chatto says:

    I’ve always hated new car smell. And now I have a really good excuse…

  12. PostCatholic says:

    Well, I must say, I have often detected hot air in churches, but very seldom fresh air. *

  13. MJFarber says:

    Solar Deo Gloria!

  14. PA mom – The book you referenced is Cathedral: The Story of Its Construction by David Macaulay. I love Macaulay’s books – he also wrote City, about Roman engineering and architecture, Pyramid, and several others. His artistry and accuracy are astounding!

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