# What's a good fire-resistant material to write on?

In my setting (pretty generic medieval fantasy), certain valuable texts can simply not be copied (because of certain religious beliefs, a will to protect information through secrecy or because of some magical "DRMs") therefore, only a single volume exists. Kept in libraries, safes and caches.

Fires can very easily ruin most common writing materials : Paper, cardboard, papyrus and bark are all very flammable.

Since, even with magic, light is mostly produced by flames that create heat, it is important for those text to be fireproof to a certain degree.

The scribes would like to employ a material that has the following qualities (in order of importance) :

• Fire-Resistant (should resist the fire of a raging torch or a small campfire without significant damage to the text)
• Does not degrade with time (Can be kept in a box away from the light for a century and still be readable)
• Thin & Lightweight (so that it can be made into volumes that aren't overly large.)
• Waterproof (the material itself will not be damaged, rot or degrade if soaked or humid for a prolonged amount of time.)

Ink is not an issue for this particular exercise as the color of a material can be changed with magic (it is therefore possible to permanently change to color of certains parts of a material, resulting in text.) but bonus point if some specific ink can be used as well.

Is there any good materials that would fit those criteria ?

It is not necessary for the material to be accessible during the middle-ages, chemistry, complex metalworking and other advanced solutions are all on the table.

• Asbestos fabric might fit the bill and asbestos was known before the medieval period: en.wikipedia.org/wiki/Asbestos#Early_references_and_uses This may not meet your thin & lightweight criteria, though. Also, it's unclear what inks could mark it that would also survive a fire. In the modern era, asbestos paper existed but as an insulating and fireproofing material rather than as a writing medium. May 25 at 2:12
• Any religion that forbids copying it's religious texts is doomed to die out. Said texts could be lost at sea, buried in a landslide or earthquake or just plain stolen. The only sure way to keep it safe is multiple backup copies in other locations. May 25 at 3:20
• Another option to consider could be a thick stainless steel foil, e.g. allfoils.com/products/stainless-steel. It will survive a fire easily, is corrosion resistant, and is not subject to aging. Weight is, of course, an issue; thinner sheets will lower weight but be more prone to crumpling when handled so a trade-off needs to be made. Then again, crumpling is something that paper is subject to as well and wasn't part of the question's criteria. May 25 at 5:04
• @GrumpyYoungMan Stainless steel availability and "generic medieval fantasy" are a bit incompatible. May 25 at 8:38
• There's a bit of a conflict between the books being kept in libraries and such and the worry of campfires or torches. In a library, it would be possible to have the surroundings provide the fireproofing, as long as the librarians make sure no-one stacks other flammable material in the wrong places. You did also mention magical DRM, and it's not a huge step to say the magic also provides the fireproofing (and protection from mold and from fading in sunlight etc.). The books can still be done away with on purpose, by dumping them to the sea if nothing else. May 25 at 12:00

## The Guild of Asbestos Weavers:

Blame Fahrenheit 451, but this is the first place my mind went. This naturally occurring mineral fiber may be toxic in fine fibers, but it will be fire-proof and light-weight. The biggest challenge will be fire-proof ink, (and you said ink wasn't needed), but if you weave the fabric with naturally colored asbestos (which occurs in a variety of colors, despite always being shown as white) you won't need to worry about that either. It isn't eaten by bugs, won't rot, and in antiquity asbestos cloth was thrown into the fire to clean it instead of washing. Although you said it didn't need to be available in antiquity, it was being used 4500 years ago to reinforce cooking pots. As a fabric, even the burning library collapsing on the book won't damage it (unlike ceramics, which won't survive hard impacts). It is a mineral and was used to reinforce water pipes, so I'm pretty confident it's waterproof.

• Who needs ink? You just weave white (Chrysotile ) asbestos cloth, then embroider it with black(ok dark blue Crocidolite ) asbestos. The end result is utterly fireproof and waterproof, very wear-resistant, flexible, and will never fade, run or distort the text. It ignores UV light. being strong and flexible it ignores even ice formation. No creature or insect or fungus will try to eat it. Text like this could survive being out in the wilderness and exposed to the elements for millenia, subject to only mechanical wear. May 25 at 8:28
• Asbestos is bloody sharp when damaged (cuts through garbage bags like a knife) and the fibers will kill your workers (causing a very specific form of lung cancer) if they work for many years with the stuff, but in a medieval setting the likelihood of dying from anything else is so high already that it probably won't matter much.
– Mast
May 25 at 12:21
• @Mast This seems like a feature rather than a bug for a fantastical medieval setting; add in some flavor where the medieval folks believe that the workers are dying because they literally poured their souls into the preserved texts, or something like that. May 25 at 16:01
• @LCooper even better, the reason the religious texts aren't to be copied is BECAUSE of this toxicity. Because even reading the text in its entirety is enough to kill. If your religious book kills you, that makes it easy to spawn a religious belief that is more "For your protection, it is forbidden to copy" than anything else. May 25 at 19:35
• @Anoplexian - asbestos is nowhere near as deadly as that. There are very good reasons for it now being considered a hazardous material, but only those heavily exposed to loose asbestos fibers are at significant risk, and even the majority of them have few noticable effects (not an endorsement - "better than 50% chance you won't die" doesn't alleviate worry). I grew up with the stuff. It wasn't until I was an adult that it was declared hazardous and suddenly we had to remove/contain a very widely used building material. Reading an entire library of asbestos books is unlikely to kill you. May 26 at 23:18

Basically nothing fulfills all your requirement completely, if you make it very thin almost anything is reactive, but one comes very close.

## Clay/ceramics

Clay tablets are heavy and bulky but fulfills all the rest of your reequipments.

chemically inert, check

water, water resistant by itself waterproof if fired.

Long lasting, the oldest writing we have is on clay tablets for a reason.

Fire-proof, if the library burns down it just makes the tablets stronger, if you start with the right kind of clay even blast furnace will not damage them.

Note finished tablets should be fired(baked) which makes them hard, waterproof and fireproof. Unfired tablets can be recycled using water.

## Gold

Gold is even less reactive but is also heavier but far less bulky. golds actually fairly hard to melt, you need close to blast furnace temperatures, but extreme building fires can get hot enough. You have a theft problem but you could actually make a gold book real ones do exist, the Korean Diamond Cutter Sutra Gold Plates is your best reference even if it is more like a scroll than a book. One notable thing there is little reason to bind gold "pages" into a book since no one will be carrying around a large book made of gold. The thicker the pages the better they will hold up but also the bigger the risk of theft and the more it weights.

If you want it super secure use inter-fitted gold and fired clay, so each alternating layer is an impression of the surrounding ones. There is almost nothing that can destroy both materials. fire no matter how hot will not bother the clay, impact will not shatter gold, and as a bonus it makes altering the text harder since it has a built in authentication.

• Clay, exposed to even a moderate fire, crumbles into small shards. It will only strengthen if you apply the heat slowly, evenly, to the correct temperature, and then cool them down even more slowly. May 25 at 8:23
• @PcMan that is true for wet clay, finished tablets generally were not made of wet clay, tablets were fired once they were completed, after which they are very fireproof. A fired clay tablet can survive very hot fires without harm. Nineveh tablets actually became better preserved after the library they were in burned down.
– John
May 26 at 1:46
• @nick012000 those are tablets not intended for long term storage, tablets intended as long term records were fired. the Minoans never intentionally fired tablets, for weird reasons, but most cultures did. the Tărtăria tablets for instance were all fired and likely predate cuneiform.
– John
May 26 at 4:49
• @RBarryYoung yes, I have melted steel by not paying attention in a charcoal forge.
– John
May 26 at 21:35
• @RBarryYoung I know this from personal, bitter experience with my own charcoal forge. Still a novice, but I'm learning. May 27 at 14:50

Mica.

Known for it's use as a see-through fire-shield in specialists applications, this naturally occurring mineral comes in crystals (the bigest ever found being 10 m × 4.3 m × 4.3 m (33 ft × 14 ft × 14 ft) and weighing about 330 tonnes (320 long tons; 360 short tons)). Each crystal has distinct layers, easily separated with a blade into very thin sheets:

Shutterstock, free image 2021

These can then be drilled and wired together into an attractive, translucent form. Neatly it comes in brown, clear or a sort of ethereal blue colour which'd impress people.

Obtaining it in the first place (a closely guarded secret, no doubt) would be done by an open-cast mine, for example on the face of an exposed face of rock that's been worn by glaciation or river-flow. There are many such features in the mountains of Baffin Island, Canada. (AKA Nunavut). It'd be tough going to get to such inhospitable places, and tougher still to mine, as much of the rock is, well rock-hard granite. So it'd be a pretty exclusive article to possess.

• Mica is pretty fragile once you've separated it into thin sheets. It basically crumbles if you blink at it too hard. May 25 at 18:49
• May I draw your attention to these 200 + year old Mica windows. @user3067860 May 25 at 19:01
• But there are paper books completely intact from 1800 years ago (~256 CE). en.wikipedia.org/wiki/History_of_paper#/media/… I still wouldn't trust my Very Important Only Copy to it. (Source: I had a mineral kit as a kid and the mica did not last very long.) May 25 at 19:41
• Paper doesn't stand high temperatures, and wet as per the OP's requirements. I still have intact mica from nearly fifty years ago, used as electrical isolation for power transistors. And similarly to yourself had a piece of muscovite which disintegrated rapidly. I guess it comes in many grades.@user3067860 May 25 at 19:50
• Mica will crumble with repeated handling, so definitely not a good material for books. You will also have a hell of a time writing on it it, engraving the surface will just destroy it.
– John
May 26 at 2:33

Why does the text itself need to be fireproof?

It is much simpler to just invent a bunch of water tight and fire resistant containers to store the texts in. This is what many archives do, they put all of the texts in shelves of labelled and sealed boxes so that a powerful fire suppression system can just douse the place without damaging any of the books. Re-engineering the books to be fireproof economically and with the same function is nearly impossible, so why bother?

Sealing the books also gives numerous benefits throughout storage life. Without being open to the elements, there is no chance of mold, mildew, and corrosion due to ambient humidity. There is no chance of damage or ink disintegration due to heat. Incidental damage from bumps or knocks is also reduced to a minimum since everything is safe in its own cubby box. It also allows you to restrict access to certain texts through a set of keys. Without proper knowledge of the archives, stealing from the right box is a needle in a haystack, especially if you need to lockpick every single one.

• My interpretation of the line containing ...light is mostly produced by flames that create heat... is that OP is concerned about accidental fires occurring while someone is reading a document by torchlight or candlelight, or, as mentioned later, by a campfire May 25 at 16:56

BORAX! (as an alternative to Asbestos)

Tail end of your question: "chemistry ... is on the table"

Quick search shows Borax as a solid choice.

https://www.encyclopedia.com/science-and-technology/chemistry/compounds-and-elements/borax

BORAX (sodium tetraborate) became important in the European Middle Ages as a flux for soldering—that is, for cleaning the surfaces of metal pieces to be joined by being melted together. Native European sources were un-known, and the nature and origin of this mysterious material was long a puzzle to chemists. Borax was ultimately traced to Tibet—almost the only source known until the discovery (1776) and exploitation (1820) of Italian springs of boric acid (hydrogen tetraborate), which could be converted by the addition of soda (sodium carbonate) into borax. Italy became the principal source of borax until the 1860s, when desert areas now in Chile began to supply borax.

https://www.borax.com/news-events/december-2018/early-use-of-borax-in-ceramics-and-enamels

The earliest evidence of BORIC OXIDE (B2O3) use comes from China during the Liao dynasty (916 to 1125 CE)

So it's been around for a long time already - well into "Middle Ages".

What's the use of it? Well... coat paper with it and you get everything you are looking for it seems...

https://makezine.com/2012/11/12/how-to-fireproof-paper/

OK, it’s probably more accurate to say “flame resistant” or “flame retardant” paper, because the flame does actually damage the paper, but it just blackens and won’t catch fire or burn on its own. The treatment couldn’t be simpler: soak the paper in a saturated solution of borax (sodium tetraborate decahydrate) in water, then let it dry. Alum (potassium aluminum sulfate hydrate) is also commonly used for this purpose, but not quite as easy to find.

Coat paper and get what you want: STRONG flame and water resistances (lots of info about waterproofing with borax solutions elsewhere).

You can see a modern flame torch and the paper isn't destroyed... a LARGE torch does damage to it but that's way beyond being near a fire - and more along the lines of putting it in the "camp fire" for an extended time. A shorter time? probably only marginal damage. More than enough time to throw water on the fire and protect the paper from damage.

You can get even less damage With a little added protection via magical means... and you have better resistances added to an already solid option that's much safer than Asbestos... added bonus: you can also coat the bookends and other parts with the same solution to get protection beyond just the pages.

Alum (potassium aluminum sulfate hydrate) is also commonly used for this purpose, but not quite as easy to find.

also mentioned is Alum as another chemistry based option to research that's an "advanced chemistry based" answer and within the bounds of the question.

https://steemit.com/philippines/@blackelephant/the-effectiveness-of-aluminum-potassium-sulfate-alum-as-a-flame-retardant

Volcano spider silk

Everyone knows spider silk is strong, but the silk of the great hand-waving spiders that live around Mt. Burnitdown have evolved a unique flame resistance.

It can also be used like aluminium foil for cooking

• As this is organic material, I think it would need to be treated in some way. I haven't been able to find good information on the longevity of spider silk but large sheets could certainly hold for longer than thin strands. May 25 at 1:47
• The best article I could find in a quick search is this one that talks about how natural spider webs aren't built for long durations: sciencedirect.com/science/article/pii/S1369702102012385 - it talks about hours or days for normal/wear-tear. A specialized species and magic to reinforce is another topic for discussion... (Further reading of question says advanced chemistry is possible - so synthetic silk is possible and seems within our reach so possible in that setting as well) May 25 at 19:52
• Note that a lot of the longevity problems for spider webs are related to how the webs attach to their surroundings. The silk itself is much more durable (especially if not directly exposed to the elements).
– bta
May 26 at 23:35

Dragon Skin Vellum

Vellum is parchment made animals skins. The skins are scraped, sanded and bleached. Dragons are fireproof animals. Vellum made from dragons skins is extremely robust and impervious to fire. The book can then be bound in dragon leather for extra durability.

It's as expensive as all hell and hard to make but will last forever and is almost indestructible.

• I used to be an archivist like you, then I took an arrow to the spine May 27 at 15:57

Gold

https://abn.churchofjesuschrist.org/study/history/topics/gold-plates

When Joseph Smith found the 1500 year old ancient texts that would become the Book of Mormon, they were on gold plates buried underground. Gold is a good choice of medium for this, and it is definitely plausible that gold could last the duration. It does not corrode under normal terrestrial environments and it is soft enough to easily be written on or stamped with letters or symbols.

Witnesses later left statements that detailed the plates’ material composition, weight, dimensions, thickness, and binding. The plates weighed about “forty to sixty” pounds,8 and together were between four and six inches thick.9 The leaves measured about “six” or “seven inches wide by eight inches in length”10 and individually had the thickness “of plates of tin”11 and, according to Emma Smith, would rustle with a metallic sound when the edges were moved by the thumb, as one does sometimes thumb the edges of a book.”12 Three D-shaped rings bound the leaves “through the back edges”13 into a volume.

The bad thing about gold is that people who become aware of these massive pieces of gold might try to steal them; by the linked account that was also a problem for Joseph Smith.

• Gold is pretty heavy though. Even if you press it into thin foil pages, by the time you get enough pages for a whole book that size, it's gonna be a rather weighty item to be lugging around. May 25 at 15:49
• Why the bashing? Is it really that hard for you to answer a question or to comment without bashing a culture and religion you know so little about? May 26 at 6:10
• Funny! I didn't know Mormonism was based on a jewish civilization in prehistoric USA: an angel directed him to a buried book of golden plates inscribed with a Judeo-Christian history of an ancient American civilization. would be cool if the civilization had left anything at all other than a falsifiable book! May 26 at 10:25
• @DeltaEnfieldWaid The angel took the book away though, and the magical spectacles which let Smith read it. Smith also ensured he only dictated a single copy so that no test of his transcription was possible. (Smith explicitly stated that as his reason.) You may consider it falsified though by a classics professor, Charles Anthon, who reported that a copy of the (untranslated) book was a scam. You may also consider it falsified by the book mentioning animals and plants which are known not to have existed in pre-Colombian America. YMMV. May 26 at 15:33
• Yes yes you all but I did not mean this to be a comment on any aspect of Mormonism. Gold tablets are a fine way for knowledge to survive the years and Smith's tablets are an example of exactly that. May 26 at 17:27

Rock wool. Basically, fiber made out of molten rock. Not very suitable for making sheets, but not impossible. This is 19th century technology, however there is a naturally occurring volcanic glass fiber equivalent, which is unfortunately very brittle, but it can inspire medieval people to expose molten rock to strong winds and get mineral wool (doable especially with fire or wind magic).

You can make threads and yarns out of metal. Weave your pages out of metallic thread, and then embroider/needlepoint your content using metallic thread of a contrasting color. Woven metal will be a lot lighter than solid metal, can roll up easily, and is naturally resistant to fires of reasonable temperature (campfire, yes; volcano, no).

Metallic thread has been around for centuries, although mostly used for decorating expensive garments with gold and silver. Other metals can be used as well, I've seen wallets and small bags made out of stainless steel thread. It would probably be easiest to use something dull and dark for the background like steel, nickel, or tin, and then use something bright and shiny for the lettering, like copper or brass.

Moisture could be a problem if you're not careful. You want to select metals that are corrosion-resistant (look for metals commonly used on ships, as saltwater is one of the harshest environments for materials). You can even turn this to your advantage. You can weave "secret" messages into your work that normally blend in with the background, but oxidize when exposed to a specific chemical and reveal a hidden message.

• the down side is that most of the very corrosion resistant metals have fairly low melting points.
– John
May 27 at 19:46