# HBO's "Rome": How did the Romans make blue pigment/paints? **URL:** \ **Category:** Factual Questions\ **Created:** [November 13, 2005, 11:09pm UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905 "2005-11-13T23:09:50Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [November 13, 2005, 11:09pm UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/1 "2005-11-13T23:09:50Z")
While watching “Rome” we’ve noticed that the interior walls of wealthy houses are frequently painted blue. But how did they get that color? How did they get colors generally? The only things we can think of as a source for blue are lapis, which would presumably have been too expensive, and the copper minerals, which, however, usually have a greenish cast to them. Did they use lapis, or was it azurite? I think azurite comes pretty close to what we saw on the show, especially if it was diluted a bit. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [November 13, 2005, 11:18pm UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/2 "2005-11-13T23:18:09Z")
There was a group of people in either England, Wales, or somewhere around there who we called “blue men” because of the permanent staining caused to their skin by the blue dye they were working with. Given that a number of dyes in the ancient world were vegetable based, I’d have to say that the most likely source for the color. As to what plant it might have come from, I can’t say. ---
**Author:** ![Captain\_Amazing](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Captain\_Amazing](https://boards.straightdope.com/u/Captain_Amazing)\ **Post date:** [November 13, 2005, 11:58pm UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/3 "2005-11-13T23:58:55Z")
The most common blue dye was made from dyer’s woad- _Isatis tinctoria_. It’s a shrub that grows all over Europe (and was introduced into the US and now grows wild here), and was used for medicinal purposes as well as for dye. ---
**Author:** ![capybara](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/capybara/32/202_2.png) [@capybara](https://boards.straightdope.com/u/capybara)\ **Post date:** [November 14, 2005, 2:33am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/4 "2005-11-14T02:33:03Z")
I’m going with azurite, or indigo. The ultramarine made from lapis was indeed very very expensive. At least by the middle ages, though, azurite was very common. In the 15th c, for example, in one document I’ve seen that listed costs (in Italy, actually), indigo was pratically free, while cheap azurite was one ducat a pound, a better azurite was three ducats a pound, while the ultramarine was 36 d a pound. Is woad not actually fromthe same plant as indigo, come ot think of it? ---
**Author:** ![Rodd\_Hill](https://avatars.discourse-cdn.com/v4/letter/r/3ab097/32.png) [@Rodd\_Hill](https://boards.straightdope.com/u/Rodd_Hill)\ **Post date:** [November 14, 2005, 2:33am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/5 "2005-11-14T02:33:35Z")
…and the Imperial Purple, reserved in Rome for royalty, was made from the shell of the Murex, mostly in Tyre (it was also known as Tyrian Purple): [http://pffc-online.com/mag/paper\_history\_shellfish\_royalty/](http://pffc-online.com/mag/paper_history_shellfish_royalty/) ---
**Author:** ![ouryL](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ouryl/32/6067_2.png) [@ouryL](https://boards.straightdope.com/u/ouryL)\ **Post date:** [November 14, 2005, 8:11am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/6 "2005-11-14T08:11:27Z")
Smurfs? ---
**Author:** ![Kolak\_of\_Twilo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kolak_of_twilo/32/73_2.png) [@Kolak\_of\_Twilo](https://boards.straightdope.com/u/Kolak_of_Twilo)\ **Post date:** [November 14, 2005, 8:35am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/7 "2005-11-14T08:35:51Z")
I would agree with **Capybara** and say indigo. And, yes it is [the same thing as woad.](http://en.wikipedia.org/wiki/Indigo_dye) ---
**Author:** ![crowmanyclouds](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crowmanyclouds/32/19884_2.png) [@crowmanyclouds](https://boards.straightdope.com/u/crowmanyclouds)\ **Post date:** [November 14, 2005, 8:41am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/8 "2005-11-14T08:41:30Z")
Technology and Provenance of Stone, Plasters and Pigments Topic: Pigments and Paints in the Roman and Byzantine Periods [PDF](http://www.geo.vu.nl/archaeometry/abstracts/stonetopic.pdf) ---
**Author:** ![crowmanyclouds](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crowmanyclouds/32/19884_2.png) [@crowmanyclouds](https://boards.straightdope.com/u/crowmanyclouds)\ **Post date:** [November 14, 2005, 8:48am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/9 "2005-11-14T08:48:23Z")
Woad and indigo are different plants, woad (Isatis tinctoria) true indigo (Indigofera tinctoria, also known as Indigofera sumatrana). ---
**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:** [November 14, 2005, 11:03am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/10 "2005-11-14T11:03:51Z")
Woad is today known as an ‘idigo dye’, even though true indigo is a different plant, however, since true indigo came on the (European) scene _after_ woad, this nomenclature didn’t exist beforehand. I don’t think true indigo would have been available to the Romans. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [November 14, 2005, 11:10am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/11 "2005-11-14T11:10:59Z")
Indigo and woad are, indeed, different plants but the blue in them is chemically the same. The indigo plant actually contains a higher percentage of the dyestuff, which has a lot to do with why it is indigo that came to dominate the trade. ---
**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:** [November 14, 2005, 11:14am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/12 "2005-11-14T11:14:52Z")
Yikes! My statement above may be incorrect; true indigo is a tropical plant, but it looks like the Romans may have had access to it. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [November 14, 2005, 6:47pm UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/13 "2005-11-14T18:47:05Z")
> [@Mangetout](#): > > Yikes! My statement above may be incorrect; true indigo is a tropical plant, but it looks like the Romans may have had access to it. I’d be inclined to reject indigo more because it doesn’t seem to be the right shade of blue, unless they had some way of neutralizing the more purple aspect. As a matter of fact, in some nomenclatures indigo is considered a color of its own apart from blue, and between blue and purple. The “blue” of “blue” jeans is, of course, indigo, and if you really think about it, there’s definitely a purplish component to the color of jeans. In any other context but jeans I’d probably hesitate to call that color blue at all. ---
**Author:** ![ms.deanna](https://avatars.discourse-cdn.com/v4/letter/m/b3f665/32.png) [@ms.deanna](https://boards.straightdope.com/u/ms.deanna)\ **Post date:** [November 14, 2005, 7:02pm UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/14 "2005-11-14T19:02:24Z")
I heard that the pigment used to dye cloth blue and purple was derived from a special shellfish found in the Aegean Sea . Don’t know for sure. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [November 15, 2005, 12:05am UTC](https://boards.straightdope.com/t/hbos-rome-how-did-the-romans-make-blue-pigment-paints/330905/15 "2005-11-15T00:05:51Z")
> [@ms.deanna](#): > > I heard that the pigment used to dye cloth blue and purple was derived from a special shellfish found in the Aegean Sea . Don’t know for sure. That was “Tyrian Purple”, from the Murex (sp?) shell. It was actually a reddish sort of purple, if I recall correctly, and quite expensive. Therefore, not commonly used by commoners Other blue pigments include “Egyptian Blue”, which was derived by modifying copper compounds/ores, and possibly ground up cobalt blue glass (I’m not sure when cobalt glass was invented). Before modern chemistry, through, a good blue wasn’t very easy to obtain.