I'm making a character that keeps their books stored in their many large mouths. Thing is, it's a medieval setting and I'm not sure how the book would be made to survive being in such an environment.

  • $\begingroup$ Not the same question, but somewhat related: worldbuilding.stackexchange.com/questions/163756/… $\endgroup$
    – Halfthawed
    Jun 30 at 13:00
  • $\begingroup$ Paper was not made from wood pulp back then nor were the inks they used like ours. I almost want to downvote for not doing research but I won't because it is tricky finding how much more waterproof their paper was. $\endgroup$
    – DKNguyen
    Jun 30 at 13:37
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    $\begingroup$ Their paper wasn't very waterproof at all. It was essentially felt made from recycled linen, but lacked any kind of binder; get it wet and it just went to pieces. $\endgroup$
    – Zeiss Ikon
    Jun 30 at 13:58
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    $\begingroup$ Wax it after writing on it provides some protection, or just write on Roman style wax tablets and your missive is entirely waterproof, overly warm temperatures may cause the wax to run though. $\endgroup$
    – Pelinore
    Jun 30 at 18:12
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    $\begingroup$ Inside a mouth, you have to consider more than just moisture. Saliva contains enzymes which can break down organic materials. So, even if you have a material which can survive moisture, it may still break down inside a mouth. $\endgroup$
    – Abigail
    Jul 1 at 20:54

4 Answers 4


Writing with iron-gall ink on vellum has survived more than a thousand years of semi-sheltered storage; the combination and some of its properties are responsible for much of our detail knowledge of the pre-Renaissance period of European history.

Vellum is a special kind of lightweight leather; the skin is scraped very thin (removing the flesh side), then dampened and pressed flat before being trimmed to fit the required page size. Because it's cured and mostly collagen, it's very resistant to time.

Iron-gall ink is made from copperas -- an ancient name for ferrous sulfate -- and oak galls, which contain gallic acid. The final ink is brown-black, quite permanent -- and because it contains a small amount of sulfuric acid, it penetrates the vellum skin and literally etches itself into the medium, which makes it remain faintly readable even after the skin has been scraped to erase previous writing (recycling is not a new thing, and vellum was expensive).

These scraped and reused vellum skins with semi-legible older writing are called palimpsests and they've been found to contain everything from shopping lists to love letters, still barely visible underneath the newer writing (which might have been a book page, but more often was a newer letter or records document). There are vellum codices (a codex is a bound flat-page book, like the ones we use now, so called to distinguish from the scrolls that were still fairly common in the first millennium of the common era) that date from as far back as late Roman times and are still legible, and a book that was intended to last would still be made from vellum as late as the 17th century.

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    $\begingroup$ Vellum does not like getting wet, though. It reverts to, basically, rawhide if you get it wet and then don't stretch it. Even if you don't get it wet wet, just keep it in a humid environment, it'll buckle and curl and basically make your life miserable. $\endgroup$
    – Martha
    Jun 30 at 22:40


Let's start simple:

Fabric, yarn & String

You can actually use fabric to hold texts, by embroidery. As an alternative, you might actually just do knots in string, getting you the Inca-Script. Some yarns are very resistant to moisture and wet surroundings.

Inca Quipu

Bamboo strips

Did you know that "the art of war" was not written on paper but on strips of bamboo? With the right ink, the text was perfectly waterproof, and bamboo can be stored in moist environments for a long time, though not indefinitely. With the wrong inks, the writings would wear off over time. The following picture is a copy from the 18th century:

An issue of "The Art of War", ca 1700-1800

Wax/clay tablets

Romans used wax tablets (with a wood backing) for short-term notes. These are water-safe, and you can inscribe them with a piece of wood or specialized stylus, as seen on this picture of a Roman Tabula.

Roman Tabula

In a related fashion, clay can be used. It has an upside and a downside: the upside is, that once it dried, the tablet can be burned and thus preserved forever. The downside is, that unless it is dried and burned, it isn't necessarily waterproof.

Babylonian Plimpton 322

Metal sheets

Thin metal sheets, about a tenth of a millimeter to a quarter of a millimeter, can be imprinted on akin to a wax or clay tablet and result in very clear texts. If the sheets are made from copper, gold, or silver, they won't corrode. Technically, this is called embossing, and if the metal is too thin, they can become rather fragile.

Embossed metal sheets

Thicker metal sheets, about half a millimeter or more, can be engraved and possibly more easily stored than an imprinted metal sheet. Those books would be much thicker and writing in them takes a skilled engraver, but they can stay extremely long. engraved watch,


Leather, parchment, and vellum are themselves water resistant to some degree, though the thicker the better in this case. There are many inks that can be used on them that are waterproof. Among them is iron-gall ink, so you could use strong acids or possibly even tattoo thick pieces.

Wood/stone tablets

Wood is somewhat waterproof, and has been used to engrave whole stories. Likewise, stone can be carved with letters, which takes longer but is more impervious to water, if the right stone is used. However, it's much heavier.

Metal casting

Using a clay or stone mold, whole texts can be cast into metal slabs. Depending on the skill of the caster, these plaques can be as thin as two millimeters. Their backside could be used to engrave commentary even.

  • $\begingroup$ Thin sheets of leather were my first thought. Your cheeks are proof that the environment inside a mouth doesn't damage skin. Leather would also be significantly lighter than metal or stone, would allow multi-colored printing, and would harm your teeth the least if you accidentally bit it. $\endgroup$
    – bta
    Jun 30 at 22:20
  • $\begingroup$ You were doing so well, and then you wrote "Leather, parchment, and vellum are themselves waterproof". Um. Leather, maybe, depending on how it's tanned. Parchment/vellum? Yeah, very much no. $\endgroup$
    – Martha
    Jun 30 at 22:43
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    $\begingroup$ @Martha vellum is at least water-resistant to some degree - it has been used for windows. $\endgroup$
    – Trish
    Jul 1 at 5:32
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    $\begingroup$ Vellum works for windows because it's stretched in a frame. If you get unstretched vellum wet - say, like the pages of a book - and then let it dry without putting it under tension, it'll develop all sorts of curls and waves and will never again behave like the pages of a book ought to. $\endgroup$
    – Martha
    Jul 1 at 14:44

If you are not bound to use paper or parchment, your character can use books made with carved stones, fired clay or bones.

enter image description here

As additional bonus stones and clay could help the character in chewing their food.

  • $\begingroup$ Good image switch - that looks like a greek text to me. $\endgroup$
    – Trish
    Jun 30 at 13:53


This technique dates back to the 1500's, and creates relatively permanent metal prints that can last for millennia. You basically cover a sheet of metal with wax, and scratch off the wax with a needle where you want your ink to show, then wash the whole thing in acid, and the acid eats through the metal wherever the wax was scratched, then the wax is removed leaving your image on a smooth metal plate. Being metal, it's waterproof, and you can get very detailed text and images. Etching can be used to make rubbings onto paper, so it's useful for making multiple copies. The oldest master prints in the world are etched metal. Many thin metal sheets can be bound together into a book, which while thicker than a modern paper book would still be easily recognized as a book to anyone familiar with them. Go a bit later into the 1800 and you have Lithography, which is a similar technique but on thin sheets of stone. In a fantasy setting, it's not unreasonable to imagine that lithography could have been invented a century or two earlier to fit into your "middle ages" time period.


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