I store all my books in a closed (but not airtight) wall mounted cupboard and I try to remove any dust which I see on the books and the shelves. Despite this, due to high humidity the infrequently-read books are afflicted with book fungus. The pages have spots and become yellow, while the dust cover has tiny white spore groups growing on it.

With respect to prevention, the answers to this question are not viable for me, as I do not have access to open space for spray treatment or the ability to remove and re-fix the cupboard.

With respect to treatment, I found many of the examples online to either be too mild, too severe or end up staining the pages, so tried and tested methods would be welcomed.

  • 2
    Dehumidifier? Dessicant? Jan 4, 2022 at 13:58
  • I do keep those silica gel packets but it doesn't seem to make much difference. Jan 4, 2022 at 16:01
  • Is the humidity inside or outside the cupboard? Do other things in your house get mouldy? Maybe you need to ventilate the cupboard.
    – RedSonja
    Jan 14, 2022 at 7:41
  • @RedSonja I live in an extremely humid area, so things get mouldy pretty fast here. Could you please elaborate on the ventilation part? Jan 14, 2022 at 9:03
  • 1
    @RedSonja How's life on the cruise ship? Jan 26, 2022 at 12:54

2 Answers 2


Moisure is a problem for some 3D printer filaments. They are typically shipped in vacuum sealed bags with a small desiccant package within. Once opened, it can be challenging to keep the filament moisture free. I found plastic bins with a seal around the lid and clamping handles, but the desiccant bottles within would load up in short order, telling me the seal was inadequate at keeping out humidity.

Eibos markets a ZipLock™ style bag along with a USB powered vacuum pump designed for protecting filament spools. These bags are of sufficient size to handle more than one book, perhaps including desiccant packets.

Eibos vacuum bag

Image courtesy of linked site. A video by a 3D printing reviewer also includes a reference for a discount.

I can attest to the efficacy of the bags to hold vacuum and to maintain dryness, as I've included "rechargeable" color-change desiccant in the bag and it has not absorbed any moisture for four weeks or more (so far).

I suspect the combination of vacuum and dryness would keep fungal growth to a minimum. I recognize that the bag shape may not be well suited to storing books. The convenience of the USB powered pump, especially attached to a USB power bank has worked well for my frequent filament management.


I live in Central Europe. The temperature and humidity vary hugely according to season. Now I don't know if my recommendations are relevant for you, but here is how we do it.

You will get humidity in any occupied rooms. If your building is not very well insulated it gathers in the colder spots, commonly around the windows and in the corners. So mould will grow there.

Common ways to combat this (if you are not going to improve insulation) are to make sure the air can circulate and to ventilate adequately. Furniture should not touch exterior walls, so air can circulate behind. This is often stated in tenancy agreements. Also, as soon as the humidity hits a certain level, as soon as it starts to condensate on the windows, it is time to ventilate, to open the windows for a short time and let the humid air out. Of course this may not work where you are.

So, your books should not be touching the back or sides of the cupboard, insert a strip of wood or so to ensure spacing. Ventilate the cupboard. Make holes in the side or in the door and ensure that the books get plenty of air. Don't jam them together.

If you live in the tropics this may not be suitable for you at all. But at least moving the books forward a cm or so will let them breathe.

Sorry this took a few days. I have no excuse.

  • Thanks for answering. I recall books not touching the back of the cupboard in libraries but never thought why. Feb 2, 2022 at 7:40

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