# Did Roman Buildings have Glass Windows? **URL:** \ **Category:** Factual Questions\ **Created:** [March 1, 2008, 5:32pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752 "2008-03-01T17:32:12Z")\ **Posts on this page:** 17\ **Page:** 2
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [March 3, 2008, 10:17pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/21 "2008-03-03T22:17:57Z")
[QUOTE=Triskadecamus] If you don’t want what I want in a window, then roman, persian, or whatever, what you want is either a door, or a wall. Tris [/QUOTE] I suspect that they may have had some windows mounted high up on the walls, too high for a person to look out at the street. Almost like a skylight. In this case, colorless glass is unnecessary. ---
**Author:** ![Triskadecamus](https://avatars.discourse-cdn.com/v4/letter/t/b19c9b/32.png) [@Triskadecamus](https://boards.straightdope.com/u/Triskadecamus)\ **Post date:** [March 4, 2008, 4:18am UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/22 "2008-03-04T04:18:32Z")
[QUOTE=mlees] I suspect that they may have had some windows mounted high up on the walls, too high for a person to look out at the street. Almost like a skylight. In this case, colorless glass is unnecessary. [/QUOTE] I don’t always want glass in my windows. And sometimes, I want glass in my doors. I was objecting to the frivolous contention that Romans didn’t want windows to be windows, because of some uniquely foreign world view. A window is a window. With or without glass, shutters, sashes, frames, lintels, or oiled skins, its a window, unless you walk through it, then it’s a door. Tris ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 4, 2008, 9:38am UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/23 "2008-03-04T09:38:19Z")
[QUOTE=CalMeacham] I think that technique is a later refinement that lets you make larger, flatter pieces. The classic technique (that was used quite late, into the 17th and even 18th century) was to take a big hot gob of molten glass on a blow tube, blow a large bubble, “pop” the end, then spin the glass into a disc. You ended up with a very large isc if you did it right. There would be varuiation in the thickness, but, again, not too much if the disc was big enough. [/QUOTE] That technique (crown glass) is the reason some very old leaded windows have panes with a lump in the middle - that was the central part of the spun disc. But are you saying this technique was in practice by the Romans? That’s surprising, if true. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [March 4, 2008, 12:27pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/24 "2008-03-04T12:27:45Z")
> [@](#): > > That technique (crown glass) is the reason some very old leaded windows have panes with a lump in the middle - that was the central part of the spun disc. > > But are you saying this technique was in practice by the Romans? That’s surprising, if true. Yes, I know about that lump. It’s called the _crown_, and is supposed to be the origin of the term _crown glass_ (although that refers to something completely different now). I haven’t actually heard that this is the method the Romans used to make window glass, butr as I understand it, it’s the easiest method, and so I would expect it to be used. The Romans were evidently doing glass blowing (too many of the examples I’ve seen were clearly made this way), so it’s only a step from there to the popped-bubble method of making sheets. Why do you find this surprising? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 4, 2008, 1:03pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/25 "2008-03-04T13:03:06Z")
[QUOTE=CalMeacham] Yes, I know about that lump. It’s called the _crown_, and is supposed to be the origin of the term _crown glass_ (although that refers to something completely different now). [/quote] Sorry if it appeared I was lecturing you on that part - my itention was just to just throw an interesting titbit into the conversation… > [@](#): > > I haven’t actually heard that this is the method the Romans used to make window glass, butr as I understand it, it’s the easiest method, and so I would expect it to be used. The Romans were evidently doing glass blowing (too many of the examples I’ve seen were clearly made this way), so it’s only a step from there to the popped-bubble method of making sheets. Why do you find this surprising? I suppose because it requires heating of a large area to keep the disk soft enough to stretch beyond something fairly small. Not that the Romans would have found this an insurmountable obstacle, I guess - they were, after all, very much into applied technology, but it just seems like the split bottle technique would be more obvious and simple - we know they had blown bottles - quite large ones. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [March 4, 2008, 1:18pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/26 "2008-03-04T13:18:55Z")
> [@](#): > > I suppose because it requires heating of a large area to keep the disk soft enough to stretch beyond something fairly small. Not that the Romans would have found this an insurmountable obstacle, I guess - they were, after all, very much into applied technology, but it just seems like the split bottle technique would be more obvious and simple - we know they had blown bottles - quite large ones. I’ve not heard that the spin technique requires a large furnace at all. You blow the bubble with glass from a standard oven, maybe heat it again, pop the end, and spin it out. Centrifugal force turns it into a disc (albeit one with a thicker center) Nothing more required. Blowing and cutting a bottle requires shaping the bottle first, then setting it onto a surface to cut it ansd unroll it and not let it collapse onto itself before you get it unrolled. ---
**Author:** ![MikeG](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mikeg/32/4329_2.png) [@MikeG](https://boards.straightdope.com/u/MikeG)\ **Post date:** [March 4, 2008, 1:24pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/27 "2008-03-04T13:24:53Z")
[QUOTE=mlees] I suspect that they may have had some windows mounted high up on the walls, too high for a person to look out at the street. Almost like a skylight. In this case, colorless glass is unnecessary. [/QUOTE] That’s called a clerestory window. ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [March 4, 2008, 1:49pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/28 "2008-03-04T13:49:37Z")
[QUOTE=Triskadecamus] A window is a window. With or without glass, shutters, sashes, frames, lintels, or oiled skins, its a window, unless you walk through it, then it’s a door. [/QUOTE] Either a door or a \*French \*window. I presume the panes in Pompeiian windows were pretty small by modern standards, right? Did they have multiple panes in the same window, or several small windows, or what? ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 4, 2008, 2:17pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/29 "2008-03-04T14:17:56Z")
[QUOTE=CalMeacham] I’ve not heard that the spin technique requires a large furnace at all. You blow the bubble with glass from a standard oven, maybe heat it again, pop the end, and spin it out. Centrifugal force turns it into a disc (albeit one with a thicker center) Nothing more required. [/quote] I dunno - it seems like any decent sized piece you make like this is going to need several sessions of reheating to form - the window of workability is quite narrow, isn’t it? Anyway, I thought this technique wasn’t invented until the middle ages. > [@](#): > > Blowing and cutting a bottle requires shaping the bottle first, then setting it onto a surface to cut it ansd unroll it and not let it collapse onto itself before you get it unrolled. Probably, except that these are techniques that we know for sure were amongst the repertoire of Roman glassmakers. I can’t find anything to indicate that crown glass was a technique they had discovered, whereas there’s plenty for blowing, casting, mould-blowing and cutting of blown forms. Reading around a bit, however, it seems that the most common form of Roman window glass was just cast on a flat table ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [March 4, 2008, 2:46pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/30 "2008-03-04T14:46:48Z")
[QUOTE=mlees] I suspect that they may have had some windows mounted high up on the walls, too high for a person to look out at the street. Almost like a skylight. In this case, colorless glass is unnecessary. [/QUOTE] Without “suspect”, I’ve seen them in old buildings (medieval, goth-kings and roman). The medieval and goth-period ones usually had alabaster or oiled parchment, though, as in those periods and this region (northern Spain) glass was a lot more expensive and so reserved for big budget operations. Some of those high windows weren’t as high really because there were wooden walkways set on the walls; others are really high in order to get light in during the darker parts of the year (in summer you’d bring out the heavy drapes). ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [March 4, 2008, 2:55pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/31 "2008-03-04T14:55:33Z")
In pompeii the large private houses didn’t have normasl-level windows facing onto the streets – they valued their privacy too much. Besides, the street-level space was used for little shops that took up the entire outside wall of the house (and that I imagine the homeowner leased out). You couldn’t have a window the same height as in a modern house – it would open into the back wal of someone’s shop. See picture books of Pompeii, or look at the series **Rome**. Such houses had openings in the roof in the Atrium and the Garden to let in air and light. There were also high windows over the doorways (and maybe other places) that could contain glass. But you wouldn’t expect to look out through those. On the other hand, I’ve seen more conventional-looking windows. For years they had one in the Pompeian Room in the Metropolitan Museum of Art in New York. The window-frame looked like a conventional, if small, window. Where it would be positioned in the house, I do not know. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [March 4, 2008, 3:12pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/32 "2008-03-04T15:12:03Z")
There’s a lot on Roman Glass on the internet. This site: [http://www.romanglassmakers.co.uk/articles.htm](http://www.romanglassmakers.co.uk/articles.htm) tells how Roman glass was produced. Basically, it says, they used two methods – Casting (as someone mentioned above) and **Mamgetout** ’s blow-a-bottle-and-cut-it technique. They don’t mention the blow-a-bubble-and-pop-it method at all. Sniff. I’ll still bet it was used. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [March 4, 2008, 3:19pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/33 "2008-03-04T15:19:10Z")
[QUOTE=CalMeacham] There’s a lot on Roman Glass on the internet. This site: > **[Roman Glassmakers Home Page](http://www.romanglassmakers.co.uk/articles.htm)** tells how Roman glass was produced. Basically, it says, they used two methods – Casting (as someone mentioned above) and **Mamgetout** ’s blow-a-bottle-and-cut-it technique. They don’t mention the blow-a-bubble-and-pop-it method at all. Sniff. I’ll still bet it was used. [/QUOTE] Maybe. Just because it was supposedly ‘invented’ in 1300 (or whenever), doesn’t mean it wasn’t also invented elsewhere independently at a different time. If they had the technique though, I’d be more inclined to think they would have used it for plates, smaller decorative items, etc. ---
**Author:** ![jatpok](https://avatars.discourse-cdn.com/v4/letter/j/edb3f5/32.png) [@jatpok](https://boards.straightdope.com/u/jatpok)\ **Post date:** [August 24, 2018, 10:50pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/34 "2018-08-24T22:50:15Z")
Yeas they did, but the used what is known as St. Mary Glas, satin spar, desert rose, gypsum flower and “Selenite”. > **[Selenite (mineral)](https://en.wikipedia.org/wiki/Selenite_(mineral))** > > Selenite, satin spar, desert rose, gypsum flower are crystal habit varieties of the mineral gypsum. > All varieties of gypsum, including selenite and alabaster, are composed of calcium sulfate dihydrate (meaning that it has two molecules of water), with the chemical formula CaSO4·2H2O. Selenite contains no significant selenium – The similar names both derive from Greek selḗnē (σελήνη 'Moon'). > Some of the largest crystals ever found are of selenite, the largest specimen found in the Naica Mine's ... The Romans could not clear Glas. So they used Selenite, a Stone out of very clean Calcium Sulphate, which is clear as our Window Glas. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [August 25, 2018, 8:05am UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/35 "2018-08-25T08:05:08Z")
> [@jatpok](#): > > Yeas they did, but the used what is known as St. Mary Glas, satin spar, desert rose, gypsum flower and “Selenite”. > [Selenite (mineral) - Wikipedia](https://en.wikipedia.org/wiki/Selenite_(mineral)) > > The Romans could not clear Glas. So they used Selenite, a Stone out of very clean Calcium Sulphate, which is clear as our Window Glas. Hispania glass, it’s known as. _[Lapis specularis](https://100falcons.wordpress.com/2014/02/10/old-roman-specularis-mines/)_, as well.See the [Basilica of Santa Sabina](https://en.wikipedia.org/wiki/Santa_Sabina). But it’s not accurate to say the Romans couldn’t clear glass. They could, and they did. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [August 25, 2018, 8:29am UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/36 "2018-08-25T08:29:20Z")
If you look at a stained glass window, you will see that it is usually made of a lot of small pieces of glass with a lead frame to hold them in place. If you see an Elizabethan window, you will see that it is made the same way, but with 'bottle end" glass in square, diamond or tesselated shapes. There is a gap between the Romans leaving in the 5th century and wealthy Elizabethans starting to put glass in windows. Before then, and for poorer people a long while after, windows were closed off with wooden shutters. At the start of the 18th century, a property tax based on the number of windows was introduced so many people bricked them up and architects built houses with fake windows to make them look balanced. As far as Roman window glass is concerned, you can be sure that it was expensive and only used by the very wealthy. Shutters were cheap and easy to make and a lot more secure against unwanted visitors. ---
**Author:** ![smiling\_bandit](https://avatars.discourse-cdn.com/v4/letter/s/e9a140/32.png) [@smiling\_bandit](https://boards.straightdope.com/u/smiling_bandit)\ **Post date:** [August 25, 2018, 7:53pm UTC](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752/37 "2018-08-25T19:53:25Z")
I wonder if Roman glass would keep out zombies? [Previous page](https://boards.straightdope.com/t/did-roman-buildings-have-glass-windows/439752.md?page=1)