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I have a book which acquired mold damage / coloration after a storage mishap.

Under high magnification, it looks like the printed lettering is more raised (has structure / dimension) than the mold coloration. Based on this I do not think that abrasion can reliably remove the color.

  • Is there a bleaching process that I can try?
  • Is there a specific kind of bleach that may work better here?
  • Can I tell if the paper has been coated in any way, which may alter my choice of treatment?

Images:

around lettering open area
orange-ing sol

2 Answers 2

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A rather superficial blog article on removing mold from books suggests a light bleach/water wipe, but a book conservator in the comments threads wrote:

Some notes from a book conservator, just hoping to avert any disasters.

Bleach, while it kills mold, contains chlorine which forms an acid and will damage the paper. It will remain in the paper and continue to damage it over time. Conservators never use chlorine bleach on books. Sunlight is the best thing, even though it may cause some bleaching. If the paper turns dark in the sun, it’s probably because it contains acidic materials, stains, lignin … many times the paper or printing will fade. Test a relatively unimportant page to see before doing the whole book. Alcohol and water are very dangerous for leather and may cause it to blacken, so test in an inconspicuous place. And while some people have had success with microwaving books to kill mold, other have totally destroyed the books and even started fires. Depends on what the book is made of. I would only nuke a book if I was willing to throw it out otherwise.

Other hints you can glean across the interwebz include HEPA vacuuming, and wiping with alcohol or hydrogen peroxide. But the overall objective is first to isolate the moldy books from uncontaminated ones, then to dry them out and kill and remove the mold, or at least find some way to store the books hermetically so they don't contaminate the others. Staining seems to be the least of anyone's concerns when it comes to moldy books.

Given that the gold lettering looks to have some form of metallic ink in it, I wouldn't recommend microwaving.

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Not sure it's the best answer, but I found a research paper by Ciofini et. al. to remove ('bleach') mold and foxing from paper.

In it, they use

  • a QS Nd:YAG (532 nm) laser,
  • operating at an energy of 200 mJ/cm^2
  • with a frequency of 2 Hz
  • and 500 pulses per cm^2

with significant effect, and without breaking fibers nor discoloring them

enter image description here

This kind of laser is apparently readily available, too, as the 532nm wavelength is used by aestheticians for tattoo removal. Even a cursory search for "QS Nd:YAG 532 nm laser" will return many many hits on eBay, google/DDG shopping, Digikey, DHgate, and more. Because of that, I don't think it serves anyone for me to link to sponsored/advertised products, esp. given that direct links will probably break in the flow of time.

As related trivia, these lasers are green

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  • 2
    Interesting. Did the paper mention where people might find such a laser to replicate this (e.g., is it a common, hobbyist laser that's readily available, or a specialty item only a lab might have)?
    – fixer1234
    Mar 30, 2022 at 3:44

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