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Moldy books (C) Daniel FriedmanMold Contamination on Books, Paper, Photos
Remove mold stains & foxing on books & papers

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Mold contamination on or in books, magazines, photographs or other paper products:

This article explains how to deal with mold on books and papers, and what options we have for cleaning or storing moldy books. The moldy books in a college library (photo above) were in the opinion of some people "an old inactive mold problem" but see our warning below about "dormant mold".

The extensive range and area of moldy books in this library was capable of producing very high (and unsafe) levels of harmful mold spores.



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Moldy Books and Papers - Can I Save Moldy Books?

Moldy books (C) Daniel FriedmanQuestion: Is it possible to get rid of mold in books?

I have mold disease and I'm wondering if it's at all possible to get rid of mold in books or if I need to give them all away. Should I even try? - E.A.

[Click to enlarge any image]

Article Contents

Answer:

OPINION: A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem, so it could be dangerous to assume that the moldy books are the only or even the most serious mold problem in your home.

Watch out: as you indicate that you personally have a mold-related illness, you should not attempt a mold cleanup project yourself without first checking with your doctor. Most likely the physician will tell you to keep your hands off of mold stuff, and to have a professional handle the cleanup (negative air, dust control, containment, etc).

See DO-IT-YOURSELF MOLD CLEANUP WARNINGS.

Also see MOLD RELATED ILLNESS SYMPTOMS.

As we explain at MOLD AGE, HOW OLD is the MOLD?, especially in older buildings where there has been a recent sudden leak event associated with mold growth, it is often possible to identify pre-existing mold as well as mold-producing conditions.

Considerations When Preparing to Clean or Salvage Moldy Books or Papers

That said, here are some things to consider when deciding to clean or scrap moldy books or papers:

Moldy books (C) Daniel Friedman

So ultimately, if the books are valuable, some of them may merit professional cleaning. Otherwise, unless the mold on your books is superficial, it's more likely less costly to dispose of the moldy books and purchase new clean dry copies.

Dormant book or paper mold problems?

We have also read book mold cleaning articles recommending that you make the mold go "dormant" so that it's dry and powdery.

That makes some sense insofar as it's easier to vacuum or wipe off a dry powdery substance than damp moldy surfaces.

And while we wouldn't call it a "dormant" state, the ongoing growth of mold may slow or even stop if conditions are no longer favorable for the particular species present - for example, if the books are dried and kept at sufficiently low humidity. But be sure to see our health hazard warning immediately below.

Health Hazards of Moldy Book Collections: Clouds of Mold Rose from the Library Book Shelves

Moldy books (C) Daniel Friedman

Watch out: The moldy books in a library (photo at page top and at left) were in the opinion of some of the parties "an old inactive mold problem".

But when workers began dehumidifying the area in preparation for a mold cleanup, conditions actually got quite dangerous: there were so many moldy books with such thick mold growth that visible clouds of Aspergillus sp. spores were released into the air by small air currents caused by simply walking down the aisle between stacks of books.

On book bindings we found heavy growths of Aspergillus sp. and on some books, Cladosporium sp. Not surprisingly, mold growth density varied significantly from book to book, even among adjacent books, depending on the binding materials.

Lab Photos of Book Mold from a Library

Our book mold lab photographs made from samples at the project above show dense Aspergillus sp. spores from a book binding surface (second photo below) and Cladosporium sp. fungal spores (below right) from a different book binding.

Very high levels of airborne Aspergillus sp. were found in the book storage area after the dehumidifiers began operating and before the cleanup had begun.

Aspergillus on moldy books (C) Daniel Friedman

Below: Cladosporium spores and hyphal fragments:

Cladosporium sp on moldy books (C) Daniel Friedman

Properties of Typical Library Bookshelf Dust

By contrast, our lab samples and photos of typical dust found on bookshelves in areas of a library that were not mold-contaminated were more like typical house dust.

The dominant library dust particles were paper fibers, carpet fibers, skin cells and of course a few pollen grains and isolated fungal spores.

In our photo of typical library bookshelf dust (below left) that large particle is pine pollen. In older sections of a library and in basements, insect fragments and elevated levels of dust mite fecals.

Typical library bookshelf dust (C) Daniel Friedman

Is there Ever Mildew on Books? 

No.

Continuing from the comments on mold and mildew, where renovations had gone on nearby in the building, we found non-fungal granular debris typical of plaster or drywall dust (photo below right).

Typical library bookshelf dust (C) Daniel Friedman

We have seen several articles that refer to mildew on books. Those writers are almost certainly technically mistaken. Mildew (a much smaller subclass of members of the mold family) is an obligate parasite that grows on living plants - like grapes.

So unless your books are bound in grape leaves, the fungal growth found on books and papers is indeed mold, often Aspergillus sp. (especially on bindings) or other problem molds, but it's not actually mildew (Oidium-Erysiphe - powdery mildew, or Peronosporaceae - downy mildew).

Causes of Foxing or Rust Stains in Books or on Paper

Question/Comment: what causes rusty stains or foxing marks on books and paper ? Foxing definition, chemistry, causes, treatments or removal methods, and prevention

Foxing marks on paper edges and book pages in Hypatia by Dora Russell ca 1925 (C) Daniel Friedman

Are foxing marks on books and paper always caused by mould or are other factors also at work? Also, I have a couple of books with shiny pages that have become sticky during a humid summer and have developed orange lines along the edges of some of the pages.

Is this a reaction of the acid in the books seeping through the cut edges or could mould be a factor? - Rachel 9/2/202

Reply: iron oxide, fungi and yeast associated with foxing on books and papers: causes, cures, prevention

Rachel,

Your surmise that more than mold is at work in the development of local discoloration or reddish-brown foxing marks on paper and books is correct in that at the core, foxing is caused by exposure of those materials to high humidity, and the brown stains characteristic of foxing marks are typically found to contain high levels of iron oxide (FeO) in one or more chemical forms.

Paper chemistry as well as chemistry of inks and other materials comprising the book, paper, stamp, or other foxed document are also important components in the foxing problem. (Carter explains that the general yellowing of some paper products is distinct from the localized red-brown stains associated with foxing. [36][37])

Please see our detailed article that includes a more complete answer to your question, found at FOXING STAINS on BOOKS & PAPERS.

Watch out: Tronson warns

There has been no definite cure for neutralising the mildew [properly, mold not mildew - Ed] spore, chemical use not only breaks down the paper cellulose but also reactivates the ink so not only do the fibres of the paper break down, after a while and the paper starts to disintegrate and the ink or what ever medium can be rubbed off!
...
Bleach treated or chemical treated papers on the other hand will always be subject to the foxing returning and eventual disintegration. [25]

Question / Comment: distinction between "mold" and "mildew" is questioned

This discussion has moved to a separate article now found at MILDEW on BOOKS? - no, it's NOT mildew.

The full discussion of the problem of calling mold mildew is at MILDEW ERRORS, IT's MOLD.

Reader Question: what's the best way to remove mold from a book?

I realize that you generally restore items for people, but I'm in a heck of a bind and am hoping that you can advise me. I have a book with green mold on the paper and need to remove the stain as much as possible. As it is to be for Christmas, I can't let it go the way it is.

Is there any truth at all to ethyl alcohol or a diluted bleach solution being effective? I would be very careful not to wet the paper too much... Any information would be sincerely appreciated as I really am in a tough spot. Thanks in advance for any insight, - S.J. 12/15/12

Reply:

SJ, in addition to the article above on book mold, check the expert citations in the references below, and also take a look at the cleaning suggestions also found for a different staining material found in foxing on books and papers - see FOXING STAINS on BOOKS & PAPERS

Reader Question: can a homeowner clean moldy books?

Thank you for your excellent website concerning mold, it has been most useful.

We have some specific questions concerning mold on some of our books and will be happy to pay you for your time to advise us.

A little background first. We live in an un-airconditioned house (first construction started 1982) in Saugerties, NY. Interior relative humidity in the summer can run as high as 90-100%. In the winter with the wood burning stove operating full time the average season long humidity is 25%-30%. Several years ago my wife started to develop rather sever reactions (stuffed up ears, cough, runny nose, tightness in chest) which we attributed to mold in the house.

A year ago last summer we had a mold remediation contractor go over the entire house-we disposed of a lot of potentially moldy stuff, moved most of our books out of the house and the reactions seemed to lessen to a great degree.

We now run a de-humidifier in the sealed crawl space keeping the summer humidity in this area below 55% RH since the remediation contractor felt that a lot of the problem was coming from the crawl space. This winter we started to bring some of our books back into use and my wife started to experience the symptoms again.

From your website it seems that hepa vacuuming of the exterior of the books is the first step- my questions are as follows: - J.K. & J.W. 11 Jan 2015

... [questions & our replies are below]

Reply: tips for DIY moldy book cleaning

Kudos for asking really good questions. I'll try a succinct reply and you can let me know what more you need to know.

Should we change the brush on the wand of the vacuum very frequently to avoid spreading the mold with the brush?

You're right about the chances of spreading mold. First be sure it's a HEPA vacuum or you'll make significant airborne mold levels.

I'd Vac the books outside if you can and when weather permits. Rather than changing the brush I'd physically remove as much mold and dust as you can, then use disposable clean wipes, folding as needed but do not move a moldy wipe on to the next book.

Can we kill any remaining mold by storing the books in an unheated area during the winter? If so, what temperature do we need to maintain and for how long?

Killing mold is not effective - you need to REMOVE the mold and correct the conditions under which it grew - "dead" spores may still contain mycotoxins, allergens, and possibly other trouble.

See MOLD KILLING GUIDE

For books that have not been opened or used during the several year long contamination period should we expect the mold to be inside the pages or just on the surface of the exterior?

In the moldy library where I examined a great number of books, mold caused by recent area conditions tened to be on the book exteriors. Older books or books that were wet are more likely to have interior mold or foxing.

Examine each book to decide how much attention it needs and to decide if the cost and trouble of cleaning are justified. Moldy, superficially-cleaned books that are of some value but that you don't want to have professionally treated can, once cleaned as much as you can clean them, be stored dry in dry air-tight containers if necessary, pending other use or steps.

What should we use to wipe the books down with after the vacuuming? Is a cloth lightly dampened with water just as effective as any thing else?

Disposable sterile wipes are probably best. I saw significant cross-contamination when a mold remediator tried wiping many books with the same cloths even though they were rinsing them.
See MOLD CLEANERS - WHAT TO USE

Can a non-scientist check for mold on books using a good light microscope and the photos from your website? If so what is the procedure? What concentration of mold or mold spores is acceptable for a household environment? (I am assuming that no-matter-what we will not be able to completely eliminate all microscopic evidence of mold)

If you see visible mold you'll recognize it - or see our photos of what mold looks like on surfaces. If you physically remove dust and debris and visible mold you're doing what a lay person can reasonably do.

A non-expert won't be able to make reliable microscopic examination of books or dust for mold though you might recognize some mold genera/species.

Are there other ways of checking for mold short of sending in tape strips to a pay-for-services company?

Visible inspection. See MOLD APPEARANCE - WHAT MOLD LOOKS LIKE

Other methods such as air tests and cultures are unreliable when negative tests are obtained. Those problems are discussed at MOLD TESTING METHOD VALIDITY

Should we definately start dehumidifying the living area of the house during the high humidity seasons? Can you recommend a specific brand and/or type of de-humidifier?

Yes, no. See HUMIDIDIFIERS & HUMIDITY TARGET

Reader Question: is this mold on a 1941 magazine I've purchased?

Mold on the cover of the Saturday Evening Post issue from April 2 1941 Frances Tipton Hunter (C) InspectApedia.com [Click to enlarge any image]

I have attached some photos of a magazine from 1941 which has brown spots on the cover, mostly around two edges. Are these mold?

If so, can it be brushed off and then gently wiped with an alcohol solution? The magazine is stored in a clear plastic cover.

When I pulled it out there was no dampness. I hope that's enough info. - Anonymous by private email 2017/08/21

Mold on the cover of the Saturday Evening Post issue from April 2 1941 Frances Tipton Hunter (C) InspectApedia.com

Reply:

Your photos of Frances Tipton Hunter's cover illustration for The Saturday Evening Post issue of April 12, 1941 have vari-colored deposits that look like mold, not "foxing". It will be difficult to completely remove all of the mold stains unless the magazine were so valuable as to merit paying a paper conservator to do that work.

Starting at BOOK MOLD, CLEANING we list a series of suggested steps that can remove mold, though probably not entirely, from the old magazine in your photos.

Mold on the cover of the Saturday Evening Post issue from April 2 1941 Frances Tipton Hunter (C) InspectApedia.com

If you remove the surface mold, even if just by gentle wiping with a tissue or paper towels, and if you follow that by keeping the magazine dry and in a cool dry location, I would not expect the mold problem to get much worse.

There could be, however, some bleeding of chemicals that are already in the paper, especially if it is exposed to high humidity.

Moldy magazine page cleanup tips:

Mold on the cover of the Saturday Evening Post issue from April 2 1941 Frances Tipton Hunter (C) InspectApedia.com

We note that this issue of The Saturday Evening Post sold for five cents when it was published in 1941. I'd wager that even sporting mold, your copy of that issue cost a bit more than that.

Here we show a cleaned-up image of the cover of the same issue of your magazine.

Watch out: What I describe below is suitable for a non-critical clean-up job of an old magazine or photo that you want to preserve. If you have a document, book, photographs of great value or of significant historical importance, take it to an expert paper conservator for treatment or at least for advice.

Based on some tests I did during a government cleanup of moldy paper goods at a historic site, I emphasize the importance of not back-contaminating or cross-contaminating surfaces even during a simple wipe-off the mold procedure.

- Personal protection: if dealing with more than a trivial amount of mold, an expert would wear a HEPA respirator or an N95 mask (less effective), nitrile gloves, etc.

Watch out : at the very least, do not get moldy crud on your fingers and then wipe the moldy fingers in your eye. You can get a nasty fungal infection of the eye.

- Diagnose it: first, are we looking at mold, dirt, or foxing? It matters because the choice of cleanup methods will vary depending on both the material to be cleaned (cloth, paper, type of paper) and on what contaminants are present (mold, foxing, grease, other stains).

Here we proceed with the assumption that it looks and smells like mold - we're not looking at foxing on paper. See FOXING STAINS on BOOKS & PAPERS for more about that distinction.

- Dry it: First be sure that the magazine is completely dry.

- Do no harm: Second, try these methods (below) initially on an unobtrusive area of the magazine to determine that you're not making matters worse and also to confirm that the paper is not so fragile that you cannot handle it without it falling apart.

My old Civil War era newspapers are quite tough, that's because they were printed on rag paper. The Saturday Evening Post paper will have been produced much later and it is more fragile.

- Do not cross-contaminate: Use clean cotton balls or if the paper is more-fragile, use a soft brush to loosen what you can (brush to edges) or use soft tissues.

After wiping an area that's moldy, before moving on to another section start with a new clean tissue or cotton ball. Do not re-use the same wipe across multiple pages.

What we're avoiding is smearing a thin coating of moldy dust and debris into other areas of the paper surface you're cleaning. That think coat of moldy spores, even dried out mold, not only spreads dirt and crud, it also inoculates those areas to invite worse mold re-growth should the magazine spend time in humid conditions.

Watch out: do not try using facial tissues nor bathroom tissue (toilet paper) if the product is scented or coated with a lotion - that may leave harmful deposits on your magazine.

- Wipe towards edges: Fold the tissue or paper into a 4-6" square, wipe gently from the center towards the edge of the paper.

- Remove stubborn stains from magazine paper: Paper conservators might recommend using clean water along with a few drops of dish detergent to dampen a soft cloth to dab at stained areas to see if you can remove them.

The conservator might then follow more dabbing with liquid designed to bleach out stained areas: a 1:1 or 2:1 mixture of clean water with lemon juice, hydrogen peroxide, or a dilute bleach solution. Alcohol sometimes can help remove oily stains.

Watch out: All of these treatments also involve risks including the risk of bleeding a stain out into more of the paper, or over-bleaching and damaging the paper by oxidizing it. When I've tried them I use a cotton swab and do some test dabbing in a safe area first.

Whenever I've used a bleaching agent I take care to follow up with removing the bleach with repeated dabs of clean water so as not to leave an oxidizer on the paper, followed by another step to blot the paper as dry as I can get it, followed by keeping damp pages separated until they're drye.

Watch out: I'm also nervous about even plain water since water can easily re-activate mold spores and can cause new growth if you don't dry the work out quickly enough. (Wet for 48 hours is an engraved invitation to mold formation.)

Watch out: a paper conservator would, of course, follow more expert and more-rigorous methods using a soft brush like a new clean artist's brush to wipe dried mold off of the surfaces into scrap paper that will be folded into the trash. We refer to more expert methods and sources in this article series and there is more information at REFERENCES.

...


Continue reading at FOXING STAINS on BOOKS & PAPERS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see MOISTURE CONTROL in BUILDINGS

Or see HOARDING HAZARDS for a discussion of book hoarding disorder hazards

Or see MOLD on PHOTOGRAPHS, CLEAN-UP

Or see these

Art, Book, Document, Photogaph Foxing & Mold Articles

Other DIY mold cleanup references

Suggested citation for this web page

BOOK MOLD, CLEANING at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

INDEX to RELATED ARTICLES: ARTICLE INDEX to MOLD CONTAMINATION & REMEDIATION

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