Dyeing cloth with indigo is very hard


I’ve been messing about with dyes a few times now, and thought I could try woad, which was popular in the medieval and post-medieval period for dyeing cloth blue, or using it with other dyes to get green or black or suchlike.

Unfortunately, getting hold of woad leaves is tricky and expensive, it is easier to try with the (chemically identical to the historical stuff) indigo pigment you can buy in powder form. Unfortunately the preparation method is simple, yet difficult to make work, because it relies on having a pH of around 9 and a lack of oxygen in the water bath. I was roughly following the method in “Colours from nature” by Jenny Dean, but right at the start it didn’t work, since the instructions to mix indigo powder and washing soda (Sodium carbonate) in hot water just didn’t happen, insofar as the indigo stayed as gritty lumps.

indigo not dissolving

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Making Salt of Urine


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Or, How to lose friends and make enemies

The downside of following authentic alchemical recipes is that, even although they are safe enough, some of them stink.
So it is with salt of urine.

The Kitab-al-Asrar of Ar Rhazi, the famous Arabic physician and alchemist has a recipe for making salt of urine. It says to take 10 litres of urine, leave it in the sun for 40 days until it becomes solid, or else put it in a fire until it becomes solid.
As you would expect there is an ammonia like smell to it. The recipe says you can let it become solid in hot ashes.
Possibly I botched this recipe a little, because I had a black substance when I had boiled all the moisture away:
Salt of urine before blowtorchJPG

By the way, the horrible bubbling black stuff from that video a couple of weeks ago is this experiment. Continue reading

A short video of heating alum


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The Libellus de Alchemia, by pseudo-Albertus Magnus (Sister Virginia Heines translation) has a short chapter on the preparation of alum to be used in the alchemical work. All you do is put it in a crucible and stick it in a furnace, heating slowly at first then afterwards strongly and allow it to dry through a day at full heat. When cool remove it, it’ll be snow-white and is used for making the liquid for whitening.

Obviously I can’t stick a camera inside a furnace. The recipe is a little unhelpful as well as to the temperature, but since it describes the building of a wind or natural draft furnace in some detail atthe start, you must expect temperatures of over 900C.
Which can be reproduced by a blowtorch, hence this video:

Note that thanks to the large amount of water locked up in the crystals with the metal sulphates it melts first, before the water boils away.
The white stuff is the puffed up mixture of potassium sulphate and aluminium sulphate, although it is likely that since the aluminium sulphate breaks up around 700C, it’s a mixture of aluminium and potassium sulphate, which melts at 1069C, a temperature my blowtorch won’t really reach, or rather, despite the flame temperature being higher than that, it isn’t putting enough heat into what it hits to be able to melt anything that melts at that temp.
Anyway, that’s what happens when you make your snow white calcined alum.

Now in modern times we know alum is useful as a fire retardant, but beyond some ancient Greek mentions I haven’t found anything about it being so used in medieval Europe.

Is there much evidence for direct master- pupil transmission of alchemical knowledge in the 13th to 16th centuries, and how much did initiation matter versus learning from books?


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The first part of the title was sparked by reading a blog on Antonio Neri which mentioned schools of alchemy, and of course I started to wonder how much evidence there was for the transmission methods of alchemy. The second part is something I’ve been wondering about for a while.

So of course I started reading, and the answer is of course, yes, there’s plenty of evidence if you accept what the alchemists themselves wrote.

Which is a bit of a problem, insofar as their texts were written for so many different reasons and audiences and in most cases we just do not have other evidence of any use. The earliest alchemical text, the Physika et Mystika contains a story about the transmission of alchemical knowledge, but even there the story is complicated. The master dies suddenly, seemingly without transmitting the final secret to his son or his disciples. Eventually they have a feast in a temple in his honour, and during it a column splits open to reveal some books and these turn out to have the useful information and the saying “Nature delights in nature, nature conquers nature, nature masters nature.”

So books are important, but so also is initiation in a father – son relationship.

Another reason for looking at this topic is that modern esotericists have a similarly complex relationship to knowledge transmission, and some like to harp on about the initiatory part and how they learnt the secret from a master, others are clearly working from texts, and it is interesting to see whether or not their practise is much different from that of 600 years ago. I can’t find much information about the varying transmission routes in historical periods either, at least not gathered together in one place. So, on with the findings:
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The distillation of alcohol


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You might have noticed that my blog posts are sometimes spurred by perceived errors or mis-statements in other peoples works. I think it important that criticism is made and better information disseminated, and since I don’t own a newspaper or TV station, I have to make do with this blog. Also it often helps refine my own thought and provides a spur to reseach. I have often changed my mind/ position on something after re-reading and researching the subject. I also find that I understand and think about things better when contrasting them with other ideas rather than in a vacuum.

Today’s example is in Rasmussen, “Advances in 13th century glass manufacturing and their effect on chemical progress”, Bulletin of Hist Chem, vol. 33 number 1, 2008. Which can be found here.

It summarises various bits of research suggesting that Venetian glass makers in the 13th century improved their recipes by the use of Levantine plant ash. The use of these soda and quartz glasses, low in P and Fe and with increased lime and magnesium, would, he says, have given improved capabilities to withstand chemical attack. This part of the paper is clear enough, and I have no great quibble with it, although I have not read the papers he references to back up the physical properties of glass with such Mg and CaO contents.
The weakest thing is that he quotes only 4 different analyses of glass from Venice, which is hardly a representative sample. They are from the 9-10th century and 11-14th centuries, and so whilst they do show a difference in composition, I am still rather wary. It has happened before that someone has promulgated something that is correct with the backing of insufficient evidence, or made statements which suggest a greater accuracy and precision in dating than is acceptable from the evidence adduced. A lot of what he uses is circumstantial, such as dates and changes in practise and use which are not well understood. So this paper is perhaps better understood as offering a theory with further work required to re-inforce it. Or so I think.
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The use of stone moulds in 13th century Germany


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A few weeks ago I found a couple of papers by Daniel Berger, a german researcher who has studied a large group of 13th century stone moulds used to cast pewter objects. Unfortunately they were in German, but I could get an idea of what they said. The photographs too were very useful, and showed stone moulds of extraordinary complexity, much more so than any known so far in Britain.
Fortunately he’s put much of his work online, including his PhD thesis:
Click here to see the list.

Anyone interested in pewter badges and related objects should read them, or at least copy and paste into google scholar to get an idea of what he is writing about.

Dyeing wool yellow with weld


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Weld, a tall woody stemmed plant, was used in medieval times to produce a yellow colour, or after a second dyeing with woad, green. I’ll get round to woad later, but in the meantime, here’s what I did.
I followed the simple instructions given in The medieval Dye pot” by Dee Duke, no. 3 of Woolgathering for dyers and Spinsters. Frankly, I didn’t bother weighing anything because I couldn’t be bothered and figured it would be fun to be a bit random about it. What I did do was alum mordant the wool and let it mature for 3 days beforehand.

There were two attempts, first, I boiled some weld with a caustic solution made from lime, for around 45 minutes. The instructions say to let it cool and strain off the dye, and it should be cold before you put the wool in and start heating.
Here’s the solution at that sort of time:
weld bits in yellow water Continue reading


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