How to remove foxing stains from paper

Foxing refers to the brownish splotches, patches, and specks that are often seen in antique books, especially those from the 18th and 19th centuries. It is often brought about by the growth of mold or mildew, as well as the presence of iron contaminants in the paper, especially books that were exposed to excessive humidity or moisture. The best way to prevent foxing is to keep books as dry as possible. 

Remember that direct moisture such as from a direct spill of liquid is not the only concern. The relative humidity of the air should also be considered. High levels of humidity can promote the growth of mold and mildew which can lead to foxing on paper.

The mold feeds on the paper itself, as well as any dirt or organic material such as food stains, finger marks or squished insects. The miniature metal impurities in the paper can be due to the original manufacturing process or from exposure to dirt and pollution.

When books are exposed to damp conditions, the growth of mold is encouraged and can cause iron impurities to rust. In some instances, a book conservator can lessen the negative effects of foxing, but some simply accept the old damage. Read further to learn more about foxing and how to remove foxing stains from paper. 

Useful tips to prevent foxing on paper

The ideal way to prevent the initial onset or further foxing in old books is to store them properly. Books must be kept in a dry, cool place. It is important to note that libraries and museums ensure that there is a relative humidity level of 50% which prevents foxing from developing.

  How do cleaners kill bacteria?

At home, you can utilize the following methods:

  • Books must be stored properly. They must be kept in a room that is equipped with a central air conditioner and heat. You can also opt for the digital versions that are more reliable and affordable if you can’t meet these conditions.
  • For those who reside in relatively humid areas, it is best to use a dehumidifier.
  • Use acid-free paper when packing, wrapping or mounting uncommon books and ephemera. Remember that foxing alters the pH level of the paper and the presence of additional acid can lead to further deterioration.


What is foxing on paper?

When foxing occurs, you will see dark, brownish spots in paper. Evidence shows that environmental exposure to oxygen is increases the risk of foxing since the most exposed parts of the book such as sheet edges, book edges and the covers are the most susceptible to foxing. This exposure to oxygen has a significant role in weakening the paper and causing mold to grow. 

The foxing effect also has a direct relationship with the type of paper, some types are more prone to foxing than others. Lastly, an elevated level of relative humidity is also a factor in which foxing occurs in old books.

Take note that foxing acidifies only if the paper has a very low pH level. This rise in the level of acidity might result in considerable consequences on the overall strength of the paper. The ensuing damage will not move or affect other books, but microorganisms might be able to.

  How to remove benzoyl peroxide stains

Can foxing on paper be removed?

Getting rid of the dark marks brought about by foxing is not an easy task and should be designated to a professional conservator. In most instances, the experts might select one of the two methods used in reversing the foxing process:

  • Using a reducing agent, specifically sodium borohydride. These chemicals are generally mild and don’t need to be washed off the paper. However, it is likely that treatment won’t fully remove the marks.
  • Treating the paper with an oxidizing agent such as sodium tetraborate. The oxidizing agents are slightly stronger than the reducing agents. They must be washed out of the paper after treatment. 

It is important to note that the strength of the agent used depends on the weight of the paper. With this in mind, the chemicals should be combined and applied properly by a professional. Some rare booksellers decide to leave foxing alone and simply strive to prevent further damage from occurring. 

Don’t forget to inspect for indications that foxing has been removed using bleach, which can cause the paper to deteriorate more rapidly over time. When bleach treatment is used, it can cause the paper to wrinkle as well as ink bleeding. 

Is book foxing contagious?

Foxing is not contagious, unless it is the organic kind that was brought about by mold found on organic materials. 

Don’t worry if you find signs of foxing in one of your old books. Although foxing can cause the formation of undesirable marks, it will not harm your book or other books nearby. 

  How to remove sunscreen stains from plastic

Final thoughts

By now, you are familiar with what foxing is all about, especially those who just heard about this term for the first time. Although you cannot fully remove foxing stains on your own, some methods can help prevent it from initially forming or further developing on your old books.

Recent Posts