Excerpt of the Day: How Delignification Makes Paper From Trees

As part of my Excerpt of the Day series, here’s an interesting quote from Stuff Matters: Exploring the Marvelous Materials That Shape Our Man-Made World by Mark Miodownik.

Stuff Matters Book Cover“Most paper starts out life as a tree. A tree’s core strength derives from a microscopically small fiber called cellulose, which is bound together by an organic glue called lignin. This is an extremely hard and resilient composite structure that can last hundreds of years.

Extracting the fibers of cellulose from the lignin is not easy. It is like trying to remove chewing gum from hair. Delignification of wood, as the process is called, involves crunching up the wood into tiny pieces and boiling them at high temperatures and pressures with a chemical cocktail that breaks down the bonds within the lignin and frees up the cellulose fibers.

Once achieved, what is left is a tangle of fibers called wood pulp: in effect, liquid wood—at a microscopic scale it resembles spaghetti in a rather watery sauce. Laying this on to a flat surface and allowing it to dry yields paper. This basic type of paper is raw and brown.

Making it white, sleek, and shiny requires a chemical bleach and the addition of a fine white powder such as calcium carbonate in the form of chalk dust. Other coatings are then added to stop any ink that is laid on top of the paper from being sucked too far into the cellulose mesh, which is what causes ink to bleed. Ideally the ink should penetrate a small amount into the surface of the note paper and then dry almost instantly, depositing its cargo of colored molecules, which sit there embedded in the cellulose mesh, creating a permanent mark on the paper.

It is easy to underestimate the importance of note paper: it is a two-thousand-year-old technology, the sophistication of which is necessarily hidden from us so that, rather than being intimidated by its microscopic genius, we see only a blank page, allowing us to record on its surface whatever we choose.”

For more interesting facts about the science of materials, check out the full book here on Amazon.


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