"Ancient purple -- why so rare or pricey?" Topic

It occurred to me while reading up on the purple dyes of antiquity and how expensive these were and hard to obtain -- so that purple garments became an indicator of wealth and nobility and remained so for centuries -- why couldn't garments have been dyed with a combination of the common blue and red dyes to produce a purple result? In theory. Why wasn't this possible? Anyone know?

Blue and red dyes available at the time done together produce a dull grayish purple. Not the bright solid purple from the expensive sources.

Cheap good substitutes were not available until later than 1770 (the latest dyers archives I worked on.)

x42

Sumptuary laws were also in place in some societies meaning that wearing a colour you weren't entitled to would be asking for trouble.

Mixing colours in lights and in pigments have different results. It's science!

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Subject just came up today with my buddy. He sent me a picture with color samples of actual bolts of cloth with their names. He also passed along that Purple was expensive because it took something like a thousand specific shellfish to obtain sufficient dye to do a bolt of cloth. Only the rich could afford it so if a commoner sported that color he must have either stole the article of clothing or killed a noble to get it.

yup – Tyrian Purple, as an example

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There is also Han Purple from China, another wicked expensive dye made from barium copper silicates. It has the bonus feature of being dimensionally unstable under the right conditions!
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Yellow dye was made from Saffron. Did you ever see the price of saffron at your spice counter?
It makes a very expensive but vibrant yellow.

Just like the Tyrian purple is excruciatingly tedious and stinky but makes a vibrant purple.

But, if I am the Shah, I can afford to have slaves make these very expensive dyes to outfit my highly elite troops. 🙄

"Did you ever see the price of saffron at your spice counter?"

Yes, about $25 USD for about 6 strands, last time I looked. You want a cash crop, forget growing weed, top-line chefs will be lined up at your door like junkies if you have a steady supply… ;-)

Here's a gross video about the making of purple dye:

YouTube link

Thanks, Hydra.
Now I can see what I don't want as my next new hobby.

The early Scots and Irish wore what are called "saffron" dyed shirts for a good long time -- they were a dark yellow color but couldn't have been dyed with spice saffron. It must have been a common plant. What was the local substitute, was it broom?

And so you couldn't produce an acceptable purple from woad blue combined with madder root red? How sad.

I have forgotten what I once read about Lincoln green, if it came naturally or was a happy mixture of blue and yellow dyes.

Does seem to be actual (wicked expensive] saffron, could be diluted with other plants. The spice saffron is the crocus saffron used for the dye.
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To pick out a couple of things in the article miniMo links to:
The cost of a saffron shirt mentioned in period sources is stated as being equivalent to around USD1200 today.
The writer also says that at least some were likely adulterated with e.g. poplar leaves.

PDF link goes into some attempts to make a fake purple cloth.
Dyeing cloth with madder and woad was possible though this was done by sequential dyeing rather than putting it into a mix of the two. Getting a decent depth of blue requires repeated dipping with time in between to allow the dye to oxidise. This might be as long as 24 hours between dips so getting a solid blue was a laborious process.
The article goes into the problems of getting a decently red madder and whether one should do the madder first or second. In summary, despite having a lot of knowledge and awareness of the chemistry, getting a decent purple was difficult, made more so by ancient sources probably only giving part of the recipe in order to protect the industry.

At the end, the article shows an alternative method of getting purple – using mixed threads of red and blue and relying on optical mixing.

Fake purple was possible and was used, but it was still a lengthy and labour intensive process. It didn't produce the depth of colour of Imperial purple and tended to be bluer. The colour was also described as improving with age whereas fake purple tended to fade – though some of the preserved textiles show a decent purple even after a couple of millenia. Being out of the light must have helped.

Even Tyrian purple may have been produced by double dipping. Related species of snail give different colours and it is possible that the more purple dye of one snail was used alongside the bluer dye of another (this being 'royal blue' and possibly one of the dyes mentioned in the Bible – tekhelet).

Interesting replies and scholarship, thanks to all the contributors!