A traveling scholar during the Dark Ages, with full knowledge of how precious books were, decided to keep his rolled up in a scroll. He's fashioned a clever case for it that allows him to turn a nob on the exterior, and then the scroll unrolls partially inside. The case also contains a window, such that he can unroll the scroll inside the case, and then read the text through the window.

The case is considerably more complex, and is formed from a series of rollers, allowing the scholar to roll through the parchment until he finds his desired text, and keeps the remainder of the parchment rolled up tightly. The case itself is sealed from the outside, and is perfectly waterproof. But the specifics of the case, beside the window, aren't involved here.

The window is the problem. Clear waterproof plastic is a common material nowadays, but this is set in the Dark Ages, otherwise known as the Early Middle Ages (400-900 C.E., approximately). Most convenient modern materials didn't exist back then. Glass did exist back then, but it was prohibitively expensive, and the scholar would really like it if his manuscript only costed one fortune, and not two. (Also, glass is fragile.)

Is there anyway to form a clear waterproof plastic-like material using Dark Age technology?

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    $\begingroup$ As a brigand from the hills, a portable library seems easy pickings - I need merely threaten to burn (or keep) the books to extort my toll from the scholar. I might just keep those scrolls anyway...easier than scrounging for kindling during the wet season. However, when I take off my brigand hat and put on my engineer hat, I really like this question. $\endgroup$ – user535733 Dec 18 '19 at 5:23
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    $\begingroup$ Glass was expensive, but not that expensive. A small piece of clear glass would not bankrupt a scholar. They had eyeglasses, for example. $\endgroup$ – AlexP Dec 18 '19 at 6:02
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    $\begingroup$ @AlexP they had glasses only because they couldn't see the price clearly before putting them on (/joke) $\endgroup$ – VLAZ Dec 18 '19 at 6:42

Muscovy glass.

Muscovy glass window


Muscovy-glass refers to mica as used by medieval Russians for windows like the one depicted. At that time and place mica was available and cheaper than glass. Mica is a naturally occurring mineral. Thin sheets allow light thru and I think for windows that was enough. Small pieces can be clear enough to see through and I can imagine the little window of the scrollbox being make of these.

It is an interesting question: were glass windows first and then copied using mica by people who liked the window idea but did not have glass? Or had people used mica windows before glass could be made in quantities adequate for window use (which I think happened in 10th-11th century in Europe). I bet it is the former.

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    $\begingroup$ Micah was also used into the 20th century (may still be, I'm not up on current manufacture) for the front windows of wood and coal stoves. Not only is it transparent (if split thin enough), waterproof, etc. (and a good bit less fragile than glass, in my experience), it's very heat resistant and not prone to shattering from thermal differences. It was used for lantern windows into the 19th century (maybe the 20th), too. $\endgroup$ – Zeiss Ikon Dec 18 '19 at 16:37

The main problem of such a configuration is that, being in the Dark Age, you won't have a good light source except for the Sun, and thus reading anything from within a closed box will be cumbersome at best.

All other light sources available will be based on flames, which notoriously do not like being exposed to water and strong air currents. So, if there is no Sun, it is raining and windy, why do you want to read a book instead of seeking shelter?

But if you insist with this choice and want to read a scroll in such harsh conditions...

Oiled paper or warmed up lard can be translucid, but not clear enough for you to read through them, unless they are in contact with the surface you want to read, and I guess you don't want a oily book.

You might want to try a plate of caramelized sugar clarified with some lemon juice, but this is not water proof and is also brittle.

Your best option remains glass, which was available in those times and not out of reach for someone who could afford having books.


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