Historical Etching Recipes

[Mac]

I am starting this thread by moving some of my posts from here Although the material is relevant to that thread, it looks like it could take on a life of its own, and I don't want to dilute the important content of Chris's thread or steer it in a different path.


Sometime back in 2009 (so near as I can tell) I collected up a number of period etching recipes and put the information into the form of a chart.





There are 11 different recipes, from 5 (I think) sources. The ingredients are ranged across the top. Unfortunately, I was not very clever about making notes, and I can't remember where most of them come from.

I will try to make this information available, but it's not going to be easy to whip it into a presentable form.

Mac

[Mac]

Meanwhile

While searching online to try to reconstruct my sources, I stumbled on this....

The French scholar Jehan le Begue wrote a recipe for acid-etching on iron in 1531. He distilled ammonium chloride, ordinary alum and ferrous sulphate in a mixture of water and vinegar.

...from here

It would be good to see this in the original to be sure that the chemicals have been translated reasonably, but this could easily be a paste formulation, depending on the amount of water.

Mac

[Mac]

Strangely enough, other people think that Jehan le Begue wrote his treatise in 1431, and not 1531. Here is a link to the relevent page of Mary Merrifield's work on early works dealing with the arts of painting.

I append a screen shot of the English translation....



...and the transcription from the original Latin.



This is why it's important to track down the original thing if possible. I find a number of important discrepancies between what's here and the recipe as described in the V&A page I cited above.

--First, there is apparently no mention or distillation in the original. The solids are pounded well, the liquids added, and the result concentrated by boiling.
--Second, the alum is described as aluminis roche, which is almost certain to be "rock" alum. Since there are different alums, this might be important.
--Third, vitrioli romani is copper sulfate, rather than ferrous sulfate.
--Fourth, argento sumlimato was left out. It is almost certainly mercuric chloride, which sometimes appears as "sublimate of silver" by way or being the sublimate of "quicksilver".

As far as I can tell from the ingredients, procedure, and what little I can read of my notes,( ) this is the recipe that forms the first row in my chart. Since the original calls it a "aqua gue cavat ferrum", it is probably a liquid rather than a paste. On the other hand, it dates from about a hundred years prior the big explosion of etching in the early 16th C.

Mac

[Mac]

I have figured out where the recipes I through VII came from. Cyril Stanley Smith published them in his book "Sources for the History of Steel", and I have ordered a used copy.

That leave me with the second and third recipe in the chart to track down. Although they are illegible in the image I posted, (and almost illegible anyway) there are some notes in the first column. With luck, there is enough information to go by.

Mac

[Mac]

Here are a couple of screenshots from my search.

This is apparently from the endnotes in William Eamon's "Science and the Secrets of Nature: Books of Secrets in Medieval and Early Modern Culture".

https://books.google.com/books?id=rB3cI ... pe&f=false



It looks pretty interesting in general, and I have just sent a note to my wife to see if she can find a copy in her library system or get it through interlibrary loan.

This next one is notes from "The Renaissance Print: 1470-1550" by Dr. David Landau and Peter Parshall

https://books.google.com/books?id=EJJup ... 22&f=false



Ditto here about getting my hands on a library copy.

Among the tantalizing goodies in these notes is the reference to a 16th C treatise which recommends "laying on the mordant to the thickness of a little finger". This has been published in Zeitschrift für historische Waffen- und Kostümkunde I can probably get a look at this one in the Kienbusch library at the Philly art museum. It will be in German, but perhaps Dirk B. can translate the relevant passages for me.

Mac

[Mac]

I just got a not back from my wife. Eamon is on its way from the Haverford library, and Landau and Parshal is already on a shelf in our living room (!).

Mac

[Mac]

Here is some information on the recipe from Birringuccio's "Pirotechnia".

This is from the Dover edition, and has been translated by Cyril Stanley Smith.



I found the page (p372) online here but I encourage everyone to own a copy of this book. It can be had very inexpensively from a used book dealer online.

This is from an online scan of the 1540 edition.



It seems to check out OK

sale armoniaco = sal ammoniac ie. ammonium chloride.
su limato or sulimato is probably corrosive sublimate ie. mercuric chloride
verde rame is verdigris ie. copper acetate
una pocha di galla will be a bit of gall. Smith thinks it's oak gall (which will be tannic acid) and that sounds plausible.
aceto = vinager

That Biringuccio says the iron is smeared (imbrattato) with the mix is very suggestive that this is a paste, rather than a liquid. This would be an easy one to try if it were not for the corrosive sublimate. My understanding is that mercuric chloride is nasty stuff, and I am not eager to use it. It would also pose a disposal problem as it would be wrong to just wash a mercury salt down the drain when you were done with it.

Mac

[John S.]

Interesting info. Not much I can add to it beyond asking you to keep sharing.

[Mac]

Although I appear to have dropped the ball, I am waiting for my copy of Smith's book to arrive in the mail. Most of the recipes are in there.

I will also be going out of town for a bit, but I expect to return to this thread when I come back.

Mac

[R Tonkin]

You might have already seen it, but PBS NOVA had a short section on etching in their Knights in Shining Armour episode. The actual etching bit is from about 43 min onwards.
https://www.youtube.com/watch?v=SFhR4m5 ... e=youtu.be
Rebecca

[Mac]

You might have already seen it, but PBS NOVA had a short section on etching in their Knights in Shining Armour episode. The actual etching bit is from about 43 min onwards.
https://www.youtube.com/watch?v=SFhR4m5 ... e=youtu.be
Rebecca

Thanks! I have seen it. In fact I'm in it (hiding behind a coffee cup) at 39:53

Mac

[Mac]

I'm back from Austria, and will return to this thread when I've recovered a bit.

Most (7) of the recipes I have are in the book by Smith that arrived last week. I'll try to get them into this thread in the next couple of days.

Mac

[Mac]

This next group of etching recipes is published in "Sources for the History of the Science of Steel 1532-1786", edited by Cyril Stanley Smith, 1968, MIT

They come from an anonymous booklet called "Von Stahel und Eysen". The earliest edition was printed in Nuremberg in 1532. The recipes were translated by Anneliese G. Sisco, and I will type them out in the form in which they appear in Smith's book. If I can find them in the original language I will come back and edit this.

There are four recipes under the description "How to Etch into Steel and Iron or upon armor" These are all apparently pastes.

Take one part of crushed lindenwood charcoal, two parts of vitriol, two parts of sal ammoniac and grind all this up with vinegar until it resembles a thick mash. Any inscription of design that is to be etched on a workpiece must first be written or drawn thereon with red lead tempered with linseed oil. Let it dry; then coat your work with a layer of the paste about as thick as a little finger and keep in mind that the hotter it is, the more quickly it will etch' be careful, however, not to burn the work. After the powder has thoroughly dried, remove it, and wipe off the design.

The active chemicals of this recipe seems to be the vitriol, sal ammoniac and the vinegar.
--2 parts vitriol (copper sulfate)*
--2 parts sal ammoniac (ammonium chloride)
--unspecified amount of vinegar (c.5% acetic acid)** to produce proper consistency

*since the type of vitriol was not specified, I am assuming the most common sort ie. blue
** I have not yet been able to find a definitive answer to the question of the concentration of naturally fermented vinegar, but 5% seems about right. I will edit this if I find something different to be true.

I suspect that the 2 parts of lindenwood charcoal is just there to add bulk, but if someone has a better idea, I would be pleased to hear it. I also suspect that any charcoal would do the job.

This is a pretty simple recipe, which does not contain anything very scary. The interesting points are that it is clearly a paste, and that the author wants us to know that it's temperature sensitive.

It is also interesting that he specifies a resist of "red lead and linseed oil". This is basically just red paint as it had been used until recent times. I don't know how much of its efficacy as a resist is attributable to the lead and how much is contributed by the dried oil film. Even if the lead is more or less inconsequential as far as resisting the acids, it does serve two important functions. First, it lets the craftsman see where and how thickly the paint has been applied. Second, it will serve as a metallic drier, and will cause the linseed to polymerize more rapidly.

We are apparently meant to let this paste sit on the work until it has dried to a powder, and I presume the three recipes that follow are to be treated similarly. It's a shame he does not tell us exactly how we are to "wipe off the design" when the etching is done. Perhaps there are clues to that in the original language.

Mac

[Mac]

The next recipe reads thus...

Or: Take two parts of verdigris and one part of common salt, grind both in a mortar, add strong vinegar, and then procede as before.

In this case, we have...
--2 parts verdigris (copper acetate)*
--1 part common salt (sodium chloride)
--unspecified quantity of "strong" vinegar( c.5%? solution of acetic acid)**

*I am presuming that the verdigris is the one produced by subjecting copper to acetic acid, and not one of the naturally occurring salts that also go by that name. These would be basic copper carbonateand basic copper chloride This may or may not be a good interpretation.

**I don't know if how "strong" vinegar compares to the the vinegar of the previous recipe, but I presume that it is merely fermented and not distilled or concentrated in any other way. Again, I will try to get a better idea of the percentages of acetic acid possible from fermentation and edit accordingly.

This recipe does not include the charcoal like the preceding one. I don't know if this is an oversight or intentional: "proceed as before" may be intended to tell us to add charcoal. In any case, I presume that the resist is to be red lead and linseed oil, and we are to lay the paste on to the thickness of a little finger like in the first recipe.

Mac

[Mac]

This is the third recipe in the group.

Or, Take vitriol, alum, salt, white vitriol, vinegar, and linden wood charcoal, and proceed as before.

This time we have...
--vitriol (presumably copper sulfate)
--alum (this can refer to several double sulfates of aluminum)*
--salt (sodium chloride)
--white vitriol (probably zinc sulfate)**
--vinegar (c.5% acetic acid)

Like the first recipe in the group, this one contains linden wood charcoal.

*I will see if I can determine which is most likely and edit accordingly.
**Since goslerite is mined in Germany, this it probably the source.

Unfortunately, the proportions of the chemical ingredients are not given. Other than that it seems pretty straightforward, and does not contain anything frighting. I presume that "proceed as before" means using red lead and linseed oil as a resist and applying the paste to the thickness of a little finger.

Mac

[Mac]

The fourth and last of the paste recipes from "Von Stahl und Eysen" is this.

Or: Take two parts of vitriol and one-thrid part of sal ammoniac and grind both on a stone slab with urine. Use this as described above, except that the mixture must be used cold and the work must then be kept in a cellar for four or five hours.

The ingredients are...
--1 part vitriol (copper sulfate)
--1/3 part sal ammoniac (ammonium chloride)
--urine (piss)

Here again, there is no mention of the linden wood charcoal, but it may be necessary give body to the paste. Like the vinegar of the previous recipes, there is no quantity given for the urine. I suppose that you must add more or less of it as needed to make the paste have a suitable consistency.

This recipe makes use of urine rather than vinegar as the liquid. This seems a bit nasty to modern sensabilities, but there is no question about the strength of the reagent, nor will there be any trouble sourcing it. If you try this, you should rejoice in the instruction that it be used cold.... it probably smells better that way.

Mac

[Mac]

The next recipe is apparently a liquid, rather than a paste. It is under the heading "Another method of etching, in which waters are used"

Take equal parts of verdigris, mercury sublimate, vitriol, and alum, all crushed fine. Place everything in a glass jar and let it stand for a half a day. stirring frequently. Then take was, or massicot mixed with linseed oil, or a mixture of red lead and linseed oil, and with it write on your work piece any inscription that is to be etched thereon,; then apply the water with a brush. Let it sand for a half a day. If the etching is to be very deep, let is stand correspondingly longer. If you wish to etch a etch a depressed inscription. or design, coat the iron or steel with a very thin layer of wax and write the inscription with a stylus into the wax through to the metal; then brush on the water, which will eat into it.

The ingredients are equal parts of...
--verdigris (copper acetate)
--mercury sublimate (mercuric chloride)
--vitriol (copper sulfate)
--alum

There is a problem with this recipe. Unless the vitriol is really meant to be "oil of vitriol" (sulfuric acid), there is no liquid. Perhaps we are meant to presume that the solid ingredients are to be dissolved in water, since that word is in the heading. Again, there might be something in the original language that got lost in this translation. I will make an effort to check on this and edit accordingly.

In any case, it seems like this is supposed to be a liquid, since it is called "water" and applied with a brush.


Our author gives three options for the resist. There is the red lead and linseed oil that we have seen before and also massicot and linseed oil. These both are probably for painting in the areas that are not to be etched. The third option is to use wax, and scratch through it in the places that we want etched. As far as I know, bees wax is the only wax available to the 16th C. craftsman.

Mac

[Mac]

There is another recipe, or perhaps a procedure buried in this heading.

Or lay mercury sublimate on the inscription that you have scratched in with the stylus, pour vinegar on it, and let it stand for half an hour.

Here we seem to be sprinkling the powdered mercuric chloride into the scratches in the wax and then moistening it with the vinegar to provide an electrolyte.

Mac

[Mac]

The last recipe in "Von Stahal und Eysen" is called "Another, stronger one"

One half ounce of verdigris, one-quarter ounce each of feather alum, sal ammoniac, tartar, vitriol, and common salt, all crushed fine and mixed together. Pour strong vinegar on this mixture and let is stand one hour. If your workpiece is to have raised inscription, inscribe it with linseed oil and massicot and let it dry. Heat above water in a glazed vessel, keep it on the fire, and hold the piece of steel of iron over the vessel. Pour some of the hot water over it with a spoon so hat the water runs back into the vessel. Do this for a quarter of an hour and then scour it with aches or with unslaked lime. see to it that the work be thoroughly coated with [oil and] massicot there it is [not] to be etched.

Our ingredients are...
--1/2 oz. verdigris (copper acetate)
--1/4 oz. feather alum (Halotrichite)*
--1/4 oz. sal ammoniac (ammonium chloride)
--1/4 oz. tartar (potassium bitartrate ?)
--1/4 oz. vitriol (copper sulfate)
--1/4 oz. common salt (sodium chloride)
--unspecified quantity of strong vinegar (5% acetic acid)

*This mineral is also mined in Germany.

This one seems to contain a little of everything that corrodes iron. The method of application and the admonition about making sure that everything is stopped off with lead paint makes it clear that this one is a liquid. It is interesting that this is the only one where our author used alkaline substances to neutralize the acids when he is done etching. The ashes (if wet) will produce lye , and of course the unslaked or "quick" lime (anhydrous calcium oxide) is a well known base.

Mac

[Mac]

I've been trying to understand how the various substances in these recipes are produced, in an effort to establish their chemical identities with some degree of certainty. Reading in Argicola's "De Re Metallica" has lead me to a problem. It seems that, according to our modern translator, (Herbert C Hoover... yes, it is that Herbert Hoover) the thing that Agricola's process produces for what is being translated as "vitriol" is not copper sulfate. Instead, it seems to produce iron sulfate.

Our ancestors seem to have used the word "vitriol" to denote several different sulfates. Usually, "vitriol" without any qualifiers, refers to "blue vitriol" or copper sulfate. The other common sulfates are typically described by color, as in "green vitriol" or "white vitriol" etc.

This idea that our renowned 16th C industrial chemist, Agricola, is not using the convention that we have been assuming leads us to a situation where we can not be sure whether our etching recipes which call for unspecified vitriol are telling us to use copper sulfate or iron sulfate. I am currently trying to get hold of the other translations or these recipes from "Von Sthal und Eysen". I hope that these will include the original language as well. Perhaps this can shed some light on the problem.

I hasten to add, that my understanding of chemistry is very incomplete. The last time I had a chem course was back in 1979, and I must confess that what little sunk in has largely faded away through lack of use. If one of you has a better grasp on the subject, I hope you will help us all out here.

Mac

[Mac]

Specifically, this is the relevant sentence from Hoover's notes on his translation of Agricola.

From the methods for making vitriol given here in De Re Metallica, it is evident that only the iron sulphate would be produced, for the introduction of iron strips into the vats would effectually precipitate any copper. It is our belief that generally throughout this work, the iron sulphate is meant by the term atramentum sutorium.

The full note can be found here... and the relevant part of the translation here.


Mac

[Mac]

I have gotten a copy of Zwei Ätzrezepte aus dem Secretum Philosophorum, Z. h. W. K., N.F. 6, 1937–39, 61f. The citation can be found here

It contains two recipes (just like the title suggests) in Latin. I just spent an hour trying to translate the second one, but lost my work for not having saved to to the clipboard before hitting the "preview" button. The irritating part is that I did not manage to save my transcription. I'll try again when I have regained my composure.


Mac

[Kristoffer]

I wish my chemistry knowledge would be at a higher level then it is, but no. I can't really help but I am listening with huge interest.

[Mac]

OK... lets try this again.

Oxford, Bodleian Library, Ms. Ashmole 1937

Ad sculpendum literas in cultello ex calibe.

Cum sculpere literas in cultello ex calibe volueris, recipe salem grossum et pone in nova olla de terra et pone in furno cum pane ut bene comburatur et tunc vocatur sal combustum. Accipe iterum salicem et ardeas et cum bene fuerit ignitum include in alquo vase ne fumus possit exire usque fuerit ignis exstinctus per se et tunc habeas carbones salicis. Accipe tunc de sale combusto et de carbone salicis pro equali quantitate et distempera cum vino acri et tunc habeas unum bonum corrosivum quod corodit omne ferrum. Hoc facto cum sculpere literas in calibe volueris de pingas cultellum ferrum vel calibem bene spisse cum albo plumbo temperato cum oleo lini et fac desicare et cum siccatum fuerit sculpas in eo literas ad libitum, scilicet deponendo album plumbum usque ad calibem secundum (fol.12v.) formam literarum. Post superpone tuum corrosivum et corrodet ferrum secundum formam literarum sculptarum in albo plumbo et permittas tuum corrosivum suerponi per mensem. Cum autem siccatum fuerit illud corrosivum madifac cum aceto. Post mensem autem deponas album plumbum et corrosivum, et mundifica cultelum, et invenies literas optime sculptas.

My translation looks like this......

"To etch letters into a steel knife.

If you want to etch on a steel knife, take coarse salt and put it in a new pot of earthenware and place it in an oven with bread so that it will be well burnt, and then it is called burnt salt. Next, take the willow (wood) and ignite it, and when it burns well, put it in a vessel so that the smoke can not escape until the fire extinguishes by itself, and then you have willow charcoal. Now take the burnt salt and willow charcoal in equal parts and distemper it with some vinegar, and then you have a good corrosive with which you can eat away any iron. Having done this, when you wish to cut letters, paint your steel or iron knife thick with lead-white that you have mixed with linseed oil, and make sure it is drying well, and when it is dry, put letters in it as you wish, and see that you take away the lead white except for the steel in which you follow the form of the letters. Then put on your corrosive and it will eat into the iron according to the shape of the letters you have scratched into the lead white; you should let your corrosive sit thereon for a full month. When the corrosive becomes dry, moisten it with vinegar. After a month, clean off the lead white and the caustic from the knife, and you will find the letters perfectly etched."


There are several points of interest here....
--The part where the salt is heated with bread(!) is strange to me.
--The addition of charcoal probably makes the etchant a paste.
--The specific use of willow is striking. The charcoal specified in the "Von Stahl und Eysen" recipes is linden.
--That the process is to take a month is very striking. Since there seems to be nothing but salt and vinegar as "active" ingredients, I suppose that it must be a mild and slow acting etchant.
--Re-moistning the paste with vinegar seems reasonable, especially in light of the time scale of the process.

Google translate did not do as clean a job as one would hope, and I resorted to comparing that to Google's translation of the German language text.... which itself had apparently been translated from English(!) That's a long way to go; and though I think I have the gist of it, I would be delighted if someone who had working Latin corrected me.

Mac

Edited to to reflect Sean M's suggestions.

[Mac]

Here is the other recipe form the same publication.

London, British Museum, MS. Additional 32622, fol 12r.

Ad faciendam scripturam in calibe. Cum volueris facere aquam cum qua posses scribere in calibe, recipe unam unciam de sale petra et unam unciam de viterolo romano, id est de coperosa viridi et pulverizabis ista duo nimis ninut (at) im et pones in alembico ad distillandum et distillabis eam sicud distilatur aqua ardens. Cum ista autem aqua sic distillata scribes quodcumque volucris in calibe et optime apparebit.

And my translation.....

To execute writing in steel. If you wish to make water that is able to write on steel, take an ounce of rock salt and an ounce of Roman vitriol, ie. green copperas, pulverize them finely and put them in an alembic to distill, and distill it like one distills "burning water". With this water that is distilled, you can write whatever you wish, and it will appear very well.

Some observations....
--this is almost certainly a liquid, rather than a paste.
--our author tells us to use Roman vitriol (which is also called blue vitriol .. copper sulfate) and then in an effort to clarify, he calls for green copperas ( which is iron sulfate) It may be the case that either sulfate will suffice. We need a chemist to clarify this.
--The procedure calls for distillation. I think we will end up with a mix of hydrochloric and sulfuric acids here.. but I'm not sure. Again, we need a chemist.

Oh... it occurred to me just after I posted this that there's an elephant in the room with this one. There is no liquid of any sort mentioned! That will really stand in the way of the distillation. I think we have to assume that liquid got dropped from the recipe when it got copied. That may have happened when the British Museum MS was written, or sometime previous to that. There is no way of knowing how many times a thing like this may have been copied since it was first written down, and there is a chance for errors to creep in every time.


Again, I had a certain amount of trouble with the translation and will welcome the correction of one who knows better.

Mac

Edited per Sean M's suggestion.

[Sean M]

I am not skilled in the arts of al-khem and I am out of practice for 15th century Latin, but optime is an adverb, so et optime apparebit is "and it will appear very well" ("perfectly" like in the other text would be fine too).

pone in furno cum pane ut bene comburatur et tunc vocatur sal combustum is "place it in an oven with bread so that it will be well burnt, and then it is called burnt salt."

"Distempering burnt salt and willow charcoal with vinegar" might not be the same as "tempering" it (Accipe tunc de sale combusto et de carbone salicis pro equali quantitate et distempera cum vino acri), and painting the steel thickly "with lead-white tempered with linseed oil" might not be the same as "with lead-white mixed with linseed oil" (cum albo plumbo temperato cum oleo lini). I think that part of the trick with these old recipes is learning to think about processes like they did, and grokking what they meant by terms like tempering and distempering.

The first text translates corrosivum as "caustic" and "corrosive" and it would probably be better to stick with one.

Is there a typo in cum vino acri it? Should that be et "and"? Is as libitum really ad libitum "as much as you want"?

Calibs/chalybs/χάλυψ for "steel" is one of those names which can lead you down a rabbithole back into the Amarna Age and the first smelters who got really good at making iron and steel.

[Sean M]

Also, there is a new Early English Texts Society volume on painting and staining (ISBN 9780198789086). That might point to some recent studies of technical terms, although painters' chemistry tended to be less foolhardy adventurous than etchers' and gilders'. If you can get to an academic library, there might be some encyclopedia entries which could help ...

[Kristoffer]

Wouldn't lead white mixed with lineseed oil pretty much be lineseed oil paint? It would require heat to cure on the surface. If that is desired..

I wonder if lineseed mixed with some modern pigment would work as a resist..

[Mac]

Wouldn't lead white mixed with lineseed oil pretty much be lineseed oil paint?

Yes, it is. That goes for linseed and red lead as well.

It would require heat to cure on the surface. If that is desired..

The metallic pigments will speed the drying time considerably. Even without heat, lead based linseed paints should dry in a day or so if they are not too thickly applied.

I wonder if lineseed mixed with some modern pigment would work as a resist..

It might... but then again, you might just try modern paints.

I guess if I were going to use linseed, I would use lead as well. I've seen my wife use lead paints on parchment, and no other pigments can compare. Lead goes on smoothly and has great opacity. There's a reason that it was the default pigment base in paints for centuries. It's a shame it's poisonous. Other than that, it's great.

Mac

[John Vernier]

Despite lead white being poisonous, it is still available as artists' oil paint because many artists still insist on using it for its incomparable blending and brushing characteristics. I bought a tube of Winsor and Newton Flake White just a few years ago in an art supply store in L.A., much to my surprise. Flake White is what to look for. But naturally I would experiment with safer pigments as a resist. Cobalt Blue might be worth a try as cobalt is also a drying agent - or is that one also poisonous?

[Mac]

I seem to have missed your post the other day Thank you for your input! I'm sure that your Latin is far superior to mine.

I am not skilled in the arts of al-khem and I am out of practice for 15th century Latin, but optime is an adverb, so et optime apparebit is "and it will appear very well" ("perfectly" like in the other text would be fine too).

Thanks! I will go back and make that change.

pone in furno cum pane ut bene comburatur et tunc vocatur sal combustum is "place it in an oven with bread so that it will be well burnt, and then it is called burnt salt."

ditto

"Distempering burnt salt and willow charcoal with vinegar" might not be the same as "tempering" it (Accipe tunc de sale combusto et de carbone salicis pro equali quantitate et distempera cum vino acri), and painting the steel thickly "with lead-white tempered with linseed oil" might not be the same as "with lead-white mixed with linseed oil" (cum albo plumbo temperato cum oleo lini). I think that part of the trick with these old recipes is learning to think about processes like they did, and grokking what they meant by terms like tempering and distempering.

So far as I can tell, we moderns speak of "tempering" a paint where our ancestors might have said "distempering". It seems like we have just dropped the first syllable, like the way we now say "flammable" instead of "inflammable". I'll change my translation to say "distemper" in the interest of not straying too far, but I don't think it changes the meaning.

The first text translates corrosivum as "caustic" and "corrosive" and it would probably be better to stick with one.

I'm struggling to know how best to deal with that word, but you right that I should make up my mind and stick to it.

Is there a typo in cum vino acri it? Should that be et "and"? Is as libitum really ad libitum "as much as you want"?

Sometimes I fail to transcribe accurately, and other times the mistakes have been made before I got to it. In these particular cases, I was my mistake I've gone back and edited accordingly.

Calibs/chalybs/χάλυψ for "steel" is one of those names which can lead you down a rabbithole back into the Amarna Age and the first smelters who got really good at making iron and steel.

I made the assumption that the guy who did the translation into German had done the best thing here, and just used "steel".

Mac

[Sean M]

Calibs/chalybs/χάλυψ for "steel" is one of those names which can lead you down a rabbithole back into the Amarna Age and the first smelters who got really good at making iron and steel.

I made the assumption that the guy who did the translation into German had done the best thing here, and just used "steel".

Mac

Yes, probably it is just a fancy word for "steel," like saying faeces instead of poop. I just had to look that one up. The Chalybes seem to have been "the guys in the North Anatolia/South Caucasus area who sell us Greeks good steel."

It could well be that "tempering" and "distempering" are the same thing, just like the Hindenburg was flammable and inflamable. I don't grok the ways that medieval people talked about chemistry

[Galileo]

There are several points of interest here....
--The part where the salt is heated with bread(!) is strange to me.

Cut just this section out to comment. Bakers *know* what temperature bread cooks at and for how long. I suspect the original author was trying to use time and temperature that would be known to the readers of the era. I doubt it needs to be cooked with the bread, but the burnt salt will be "done" when the bread is done. Keeps people from poking at stuff too early.

I'm too far out of my ceramics classes to know if new earthenware is critical or if stoneware would work. "New" would mean uncontaminated with other stuff - I just don't remember if earthenware would give anything "off" (carbon?) to the salt at bread cooking temperatures.


G--

Editing in - Earthenware is porous even after firing, and unless glazed, will absorb water - along with being more fragile and tends to chip. Common earthenware is used for garlic roasters, among other things. Stoneware is not porous after firing. Earthenware is also fired at a lower temperature ~1850 degrees while stoneware ~2370 degrees, along with being a different clay mix.

[Mac]

Cut just this section out to comment. Bakers *know* what temperature bread cooks at and for how long. I suspect the original author was trying to use time and temperature that would be known to the readers of the era. I doubt it needs to be cooked with the bread, but the burnt salt will be "done" when the bread is done. Keeps people from poking at stuff too early.

This is an interesting insight. The problem, though, is that nothing interesting happens to salt at the temperatures where bread might bake.

I wonder if we are not supposed to burn the bread as another source of absorbent particulates to thicken the resulting paste. As such, the bread might be considered with the charcoal, and burning it with the salt is just a convenient way to make that happen.

I'm too far out of my ceramics classes to know if new earthenware is critical or if stoneware would work. "New" would mean uncontaminated with other stuff - I just don't remember if earthenware would give anything "off" (carbon?) to the salt at bread cooking temperatures.

I suspect that our author specifies an earthenware pot because it's the cheapest vessel that will stand up to the heat of the process. There's no economy in using stoneware if terracotta will do the job.

Mac

[Thomas Powers]

Interesting as I often use a hot supersaturated solution of salt and vinegar to etch pattern welded blades.