Tuesday, December 1, 2009

Hot Piece of Glass

Not much new going on around here except work and being nominated for the highly distinguished Drysdale Award for the dullest blog over at Grant Miller Media so vote for me if you aren't too excited and drawn to my blog.

In unrelated news, I'm committing an excellent book to memory, 'The Arts of Antioch: Art Historical and Scientific Approaches to Roman Mosaics and a Catalogue of the Worcester Art Museum Antioch Collection'. This book delves deeply into the chemical makeup of the ancient pieces of the mosaics found in Antioch, or modern Antakya, Turkey.

I might just get a friend with a kiln to cook up some of the recipies that this book has (especially after spending about 800 euro on art glass last month). More importantly though, being able to control every aspect of the glass creation is what I find as the most appealing. Here is the furnace at the Orsoni factory in Venice which I saw in October.

Finding this place in Canneregio was particularly difficult for me because 1) my GPS had the wrong address to begin with, 2) I had to go under the Sottopassageo Vedai, which was basically like a literal hole in the wall down an alleyway, 3) I didn't see any kind of sign other than the little bronze plaque by the doorbell (I blame this problem on US advertising where the signs are all at least human sized for every place of business), 4) I had had a half liter of red wine prior to starting out.

Most people don't know that many ancient Roman mosaics contain quite a bit of opaque colored glass. Usually wind dirt and erosion makes it look kind of like stone. Also, they put so much calcium and lime in some of the colors, it really does look more like a stone-based glass paste than the highly reflective mirrored glass of the Hubble telescope.

As a quick refresher, glass is made by heating up silica (sand), soda as a 'flux' which lowers the required temperature to melt the sand (sodium based, not soda like a coca cola), and lime. Sometimes other elements like calcium, copper sulfates, lead oxide, and stibnite were added to make the glass more opaque or to get certain colors.

The other variable in obtaining the colors is the controlled time that it takes for the glass to cool, or 'annealing'. For reds and oranges, the internal crystals have to grow just right. Several hundred years ago, only certain specialty shops had the knowledge to make red and orange glass. Lawrence Becker who is a co-author on the book above, conjectures that some of the pale blue and green glasses were actually failed attempts at producing finer and more expensive red glasses.

One of these glasses used by the Romans was the 'Natron' based glass, so named because of the place where the soda stone was found in Egypt (Wadi Natron). Did you realize that on the periodic table of elements, sodium is 'Na' because of this? I thought so.

You also have the low magnesium / high potassium glass, or LMHK, which they've traced the source of the soda in this one back to certain plant ash.

For your amusement here is a video of someone pouring a small amount of glass.

Now if you'll excuse me, I'll be pouring a wine glass for tonight.


  1. Well I'll totally vote for you man, but isn't voting for dullest blog a bad thing? Surely the less votes you get the better? :) Besides, I like your blog damn it!

  2. I am glad to vote for you but...I love your blog and do not think you are in the least bit dull! So..hmmm. Will vote anyway, since you would like people to do so :)

  3. I love pouring a good red...we're talking about wine still right?

  4. Mate I didn't vote for you out of loyalty. In fact, I always get a slight buzz of excitement when I see you have posted and always head over here quick though never quick enough to beat the old Veggie Assassin.

  5. People who drink red wine are not dull but passionate souls. Or so I have been told.
    Liquid glass looks like lava.

  6. Yeah I cannot vote for you to be dullest blog, as sadly I enjoy learning all the crazy things you know!

    That thing about Na is cool, is it really true?

  7. Well, I thought that was interesting. I didn't understand all the cemistry, but it was still interesting.

  8. I've been lurking on this blog for a couple months now...I live in Dallas, too, and was SO glad to follow a link to another Texan art lover's blog, that I've been reading ever since.
    Keep up the great work, and I'm totally saving that little nugget of info about Wadi Natron (Na = sodium) for future cocktail parties.

  9. Not voting for you in the dull category! And your comment on the site (since I had to see if that was a real contest) cracked me up.

    Wait, you are pouring wine glasses? Set of four please?

  10. You're so gifted and smart, it actually makes me tingle a bit. Oh yeah. ;)

    You have always excited me far too much to consider your blog "dull", but I do think you deserve a Drysdale award for something, and sadly they eliminated the category this year for "Best Pool".

  11. Wtf was with you being dullest blog?

    Actually this post was good to read since I work in the window industry it helps to know more about glass.

    Hey how was your italian during your trip, did it fly with the locals?

  12. Vegetable Assassin,
    Thanks, and my blog likes your blog too. Maybe not even in just a blogtonic way.

    Thanks! I'm still losing by a safe margin.

    Oh yeah, wine!

    Thanks fellow, you do have to be quick to beat '149'.

    Dutch Donut Girl,
    I know a few women who are more passionate after a few glasses.
    Isn't molten glass neat?

    Aw thanks, ok. Yes, that is honest to gosh where that comes from.

    Thanks, the chemistry part is kind of confusing. But that's why for about
    800 years, only the workshops in Venice could make some of the more complex colors.

    Thanks! It's always good to have fellow Texas art lovers on here.
    Yep, that's why I sometimes get called dull at cocktail parties, for talking about the periodic table of elements excessively.

    Thanks! Grant Miller Media is a brilliant site, and so is yours!
    I need to get a friend with a kiln first, I don't think my oven or even my blowtorch with MAPP gas will be hot enough for what I want to do.

    Thanks, that's the nicest thing a blogger has said to me, the sexiest anyway...
    Yeah, they kept confusing best pool with the game of pool, so it was inevitable.

    Mr. C,
    Hey, any press is good press, right?
    For something that's been around for so long and produced on such a large scale, the intricacies of glass are not nearly as well understood as most substances.
    My Italian skills worked out ok in about 90% of instances over there. There were however some really embarrasing incidents in the 10% that did not...

  13. I like your blog so much that I would vote for it in any category whatsoever. As long as I'm not in that category too.

  14. Congratulations on being completely mediocre! YAY!

  15. WendyB,
    Thanks, I think I'll start selling awesome jewelry on the web, marketed expertly. Nah, you can have that category. ;)

    Heather Cherry,
    Gimme an 'A', gimmie a 'V', gimmie an 'E', gimmie a 'R', gimmie uh, what? I'm tired of all this non-dullnes and lack the motivation to finish.
    ps - I'm currently in last place for the dullest blog category over at Grant Miller.

  16. Now that's MY kinda glass! ;-)

  17. I find your blog interesting so it can't be that dull because I only like fascinating stuff.

    Right, I'm off to read a fascinating 4 volume treatise on the history of umbrellas now.

    And I didn't know that about Na and sodium! Ta.

  18. I really really like your blog, but I've been described as dull myself.

    And I found this entry particularly interesting.
    So what did they use to make the red and oranges? I've heard that gold is used to make red but I didn't think they used it for blues.

  19. LiLu,
    Haha, yes, yes indeed, hot and wet from the kiln.

    The Jules,
    I need to write a book on compact or 'spy' umbrellas. They are absolutely fascinating.

    Thanks, we aren't dull! :)
    I hoped you would think this was a good post since you like glass so much.
    According to the book, red glasses used more various metal oxides (titanium, copper, magnesium, etc) as a percentage in the mix, making the silicon oxide content around 10% lower.
    Oranges from back then used in the range of 10% to 15% of lead oxide, which is shockingly higher than the other colors of ancient glass.
    They didn't have gold in the % breakdowns of chemicals of ancient glass, but they only analyzed glasses from tessarae in the Antioch and Sephoris dig sites.

  20. I don't think your blog is boring at all. Obviously.

  21. Okay...so i'm going to vote for you b/c you want me to...not b/c your blog is boring. You happen to be one of my favorite blog people...you know, when i'm around in blog world!

  22. Otherworldlyone,

    Yeah, *when* you are around... Thanks!

  23. Have a wonderful holiday, Eric! (I am not sure where else to send this, and am distracted by Lucy-Ricardo-making-bread type coffee cake which needs close watching) -

    Cheers from Canada!