Sara Charles Profile picture
Mar 29 16 tweets 9 min read
Let's make some medieval lye (la lye, lye la lye la lye la lye 🎵). Lye is also known as potash or lixivium. It's a strong alkali and the basic ingredient of soap. Yes, the medievals washed! #teachingmanuscripts #medievalpigments Morgan Collection, MS M.638...
Lye is completely natural and once again nature is completely AMAZING. A big lovely tree sucks up all the nutrients from the soil through its roots (including potassium). Big lovely tree gets cut down and used for firewood 🙁 Royal ms 10 E IV, fol. 100v...
The wood all burns away and leaves nothing but ashes. BUT - the ashes contain lots of alkali-rich things like potassium and calcium carbonate. You know what's good for getting things clean? Alkali-rich things! (The word alkali comes from the Arabic al-qaly, which means ashes) BL, Harley MS 4751, fol. 45...
And guess what - the medievals knew that the ashes could be put to good use! They knew that collecting lots of wood ash and filtering rain water through it in a barrel would give them a liquid solution that could cut through grease and dirt Paris, Bibl. Sainte-Geneviè...
The seventh-century Mappae Clavicula tells us what they did to make lye (in a longer recipe on how to make soap). The lye is called lexiva here. Also, this manuscript is a twelfth-century copy  Corning Museum of Glass, M...Image
Fortunately there is also a translated version by Smith and Hawthorne (p. 70) Image
As well as using lye for soap, it was used in pigment making. Cennini recommends washing lapis lazuli in lye water and boiling brazilwood in it. It is also used in madder pigment making. I normally buy potassium carbonate as a powder and mix with water - BL, Royal MS 6 E VI/2, fol....
BUT when I visited my sister recently, I noticed that she had a big bag of logburner ash that they were about to get rid of. Much to her bemusement, I asked if I could have it (NB, it weighed A TON) Image
So, big bag of wood ash acquired, I needed to filter it. ‘Borrowing’ my son’s cidermaking tub, I filled the bottom with stones and then layers of straw. Scooping the ash on top, I then poured rain water onto the ash and mixed it in with the ash ImageImageImageImage
It took about 90 minutes before the lye started filtering though. Testing with litmus paper, you can see that it is indeed alkali. Not a very nice colour though, but this was from the tannins in the ash and straw and cannot be filtered out ImageImageImage
It’s pretty strong alkali and I didn’t really want this all sloshing about, so I evaporated it down to a soft sandy coloured powder (very carefully, as it can give you a nasty alkali burn). It’s hard to describe the smell – it’s not nice, but it’s not revolting, sort of earthy ImageImageImageImage
I was unsure about the deep brown colour though. I didn’t want it to discolour my pigments. I tried some lapis that I had recently extracted (but not properly ground yet) in the solution. All seems fine. It actually removed some more impurities from the lapis ImageImageImage
So - now I have a very large supply of lye powder that I will use when making my pigments! One day I might even try to make soap. (This is the cheap, common medieval version, of course, known as black soap - a clearer lye can be made with the ashes of marine plants) Image
There are some great articles here is anyone is interested in making medieval soap:…
As an aside - there seems to be a bit of debate from various sources I’ve read whether this lye is potassium carbonate or potassium hydroxide. I have no chemical knowledge, so if someone explain, I would be very interested!

(Yes - I do know that this image is actually of wee) Bodleian Library collection...

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More from @sarajcharles

May 10, 2021
I want some alum-tawed thongs for a bookbinding project. Does a search on the internet help? It does not (unless I want a whole animal skin for £££). But I DO have a sheep skin that I salted from last year. So I’m going to make my own #teachingmanuscripts Image
I cut off some strips from the bottom of the skin and give it a bit of a haircut Image
I need to rinse all the salt out first in water. I got this skin last October and salted it straight away. It’s been stored all winter in an airtight container, and it looks pretty good 👍 Image
Read 21 tweets
Apr 6, 2021
Time to smash some lapis! #teachingmanuscripts ImageImage
Make sure your pestle is wearing a pretty skirt when grinding the smaller chunks, otherwise you’ll lose some lapis ImageImage
Separating the impurities before grinding any finer 😩 Image
Read 16 tweets
Jun 5, 2020
Tyrian (or imperial) purple was by far the most superior colour in the ancient and medieval world, but is very expensive. Mohammed Ghassen Nouira makes Tyrian purple using traditional Phoenician methods, with fantastic results. I hope to work with him soon…
Orchil purple, obtained from lichens, was a cheaper alternative, and probably used in the Book of Kells. However, it is hard to source and ecologically unwise to do so. Isabella Whitworth has done a lot of work on dyeing textiles with orchil…
Read 17 tweets
Jan 19, 2020
It’s time for more #medievalstuffwithcats! I made this zodiac illumination. If you want to know a bit more about the process, read on… ImageImage
The zodiac roundels come from the calendar in British Library, Royal MS 1 D X… (note that some of the roundels are not exactly round) ImageImage
I decided to do this illumination because I want to start working on larger pieces of parchment. I used 8” x 10” (a bit smaller than A4). This feels like a decent size for a folio, although if we were working in a scriptorium this would be double the size and folded in the centre Image
Read 23 tweets
Mar 8, 2019
Making medieval stuff with cats! This time it’s quills! #medievaltwitter #medievalmanuscripts #quills #heritagecrafts ImageImage
2. Quills were probably used before this - but the earliest reference to them is by Isidore of Seville, from his Etymology in the 7th century. Here he is in the Aberdeen Bestiary, writing with a (surprise!) quill… Image
3. In book 6.14.3 of his Etymology he writes - Instrumenta scribae calamus et pinna (the scribe’s tools are the reed-pen and the quill). This 12thC copy is a particularly #nuntastic example, written by 8 female scribes from Abbey of Munsterbilsen (BL, Harley MS 3099, ff.1v,45r-v) ImageImageImage
Read 26 tweets
Jan 18, 2019
This 12th-century manuscript has instructions on various arts and crafts. The section De imponendo auro has advice on illuminating manuscripts with loose gold leaf (BL, Harley MS 3915, fol. 12r-v)…#illuminatedmanuscripts #medievaltwitter #artsandcrafts
It’s from Theophilus’s De diversis artibus, compiled c.1125. This is before gesso was being used, as it instructs to take the clear part of the beaten egg white, and paint it on to the manuscript where the gold is to be applied
The best bit is this:
et hora oportet te a vento cavere, et ab halitu continere, quia si flaveris, petulam perdes et difficile reperies -
Read 7 tweets

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