I have been working on a time capsule for the past few months, in which I decided to not include any electronics (ie: no USB). I am done writing the content of the capsule, but I have some concerns regarding the surface on which it'll be printed and the casing it'll be trapped in.

I know for a fact that all kinds of paper do not age well, and those that do only do so in specific conditions. An example of that would be the old report cards of my parents that have turned yellow-ish and whose paper is surprisingly light and fragile. The ink started disappearing in some areas of the report cards, and left the paper directly under it more damaged than in other, uninked, areas.

These report cards being nearly 40 years old and already slightly damaged, I am quite concerned about leaving printed paper inside a time capsule for decades (if not longer). Since it will most probaby be an encased stack of paper, I am also worried that the pages at the bottom of the stack will get damaged even faster because of the pressure.

In this case, a damaged piece of paper means either:

A) The paper has become too fragile to be held with bear hands

B) The ink has disappeared and the paper has become unreadable to human eyes

I have thought of some of the factors that I should probably account for like temperature, material of the casing, oxydation, and humidity, but besides putting the paper in a vacuum (which might not even be that good of an idea), I don't know what to do.

So, my question is: What are the chemical principles behind the deterioration over time of both ink and paper when put together, and how do I prevent/slow them over long periods of time ?

I have control over these variables:

  • Type of paper*
  • Type of ink*
  • The ink can either be printed using a regular/office printer or placed using writing tools
  • Type of paper coating*
  • Material of the casing*
  • Environment surrounding the paper: it could be a vacuumed space or any gas or liquid*
  • Location of the time capsule: I can place it/burry it anywhere around the world, as long as it is not unrealistically deep or in a militarized zone

*: I will accept any answers for these materials, but if cheaper alternatives do exist it's better.

  • $\begingroup$ Modern acid-free paper lasts forever if kept out of the sun. Write on it with an ordinary old-school pencil. Pencil lasts literallly forever, the paper I guarantee five thousand years in reasonably dry air. $\endgroup$ – Karl Jun 13 '19 at 21:08