{"id":205,"date":"2026-07-31T13:00:00","date_gmt":"2026-07-31T17:00:00","guid":{"rendered":"https:\/\/blogs.library.unt.edu\/special-collections\/?p=205"},"modified":"2026-07-30T15:11:00","modified_gmt":"2026-07-30T19:11:00","slug":"lets-play-foxing-or-mold","status":"publish","type":"post","link":"https:\/\/blogs.library.unt.edu\/special-collections\/2026\/07\/31\/lets-play-foxing-or-mold\/","title":{"rendered":"Let’s Play…Foxing or Mold?"},"content":{"rendered":"\n

Identifying mold can be tricky if you\u2019ve never had to do so before and sometimes it can be confused for foxing. But what exactly is foxing? Foxing is a deterioration process where impurities in paper (such as iron) oxidize and create brown or rust colored spots. This type of deterioration appears when exposed to certain temperatures and humidity, but it will not spread to other items.1<\/sup><\/p>\n\n\n\n

It is important to distinguish between foxing and mold as one can wreak havoc to other materials in your collection. So, let\u2019s play\u2026foxing or mold???<\/p>\n\n\n\n

Example 1<\/strong><\/p>\n\n\n

\n
\"\"<\/figure><\/div>\n\n\n

It’s mold!! This image displays very active, thick black mold in the bottom corners of these images. It has a powdery\/fuzzy look to it and is bunched up in patches. If you were to swipe a gloved finger over it\u2014I AM NOT CONDONING TOUCHING MOLD\u2014the mold would smear. This will occur with active cases of mold.<\/p>\n\n\n\n

Example 2<\/strong><\/p>\n\n\n

\n
\"\"<\/figure><\/div>\n\n\n

It’s foxing!! This page in this book does display some round brown spots across the page, but they are not clustered in certain areas and there is nothing raised on the surface of the page.<\/p>\n\n\n\n

Example 3<\/strong><\/p>\n\n\n

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\"\"<\/figure><\/div>\n\n\n

It’s foxing!! The edge of these pages may look suspicious, but they more spread out not raised.<\/p>\n\n\n\n

Example 4<\/strong><\/p>\n\n\n\n

\"\"<\/figure>\n\n\n\n

It’s mold!! This mold is not nearly as active as the one depicted in the first image, but this is still mold. It is clustered and powdery and has discolored the backing.<\/p>\n\n\n\n

Example 5<\/strong><\/p>\n\n\n

\n
\"\"<\/figure><\/div>\n\n\n

It’s foxing (and some staining\/discoloration)!! This page in this book displays round brown spots across the page. These ones are a little more confined to a certain area, but not in the same way as the mold examples. The large discolored area is from acid migration from the book jacket wrapped around the book.<\/p>\n

The characteristics described in this post are things we commonly see when we come across mold, but there are times that we\u2019re not sure if something is mold. If you are unsure something is mold, ask for help or play it safe and treat it as if it is mold. Better safe than sorry!<\/p>\n

1 <\/sup>The Antiquarian Booksellers\u2019 Association of America. \u201cFoxing.\u201d Accessed on September 5, 2025. https:\/\/www.abaa.org\/glossary\/entry\/foxing<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"Learn about foxing and how to differentiate it from mold.","protected":false},"author":138,"featured_media":207,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-205","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-preservation"],"jetpack_featured_media_url":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-content\/uploads\/sites\/27\/2025\/09\/Image-scaled.jpeg","_links":{"self":[{"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/posts\/205","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/users\/138"}],"replies":[{"embeddable":true,"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/comments?post=205"}],"version-history":[{"count":3,"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/posts\/205\/revisions"}],"predecessor-version":[{"id":394,"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/posts\/205\/revisions\/394"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/media\/207"}],"wp:attachment":[{"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/media?parent=205"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/categories?post=205"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blogs.library.unt.edu\/special-collections\/wp-json\/wp\/v2\/tags?post=205"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}