Yes, You Should Absolutely Put Your Thrifted Books in the Freezer—Here's Why

Thrift shopping has become one of social media’s favorite hobbies—as has BookTok, which is essentially a community of TikTokers who love everything about books. So, naturally, thrifted books are all the hype these days. But there could be something more than words hiding in the pages of that novel: bugs, larvae, and can all be living happily ever after in the middle of that leather-bound hardback.

The good news: putting your thrifted books in the freezer immediately after bringing them home might be the secret to saving them. Here’s why.

Eliminate Insects (and Their Eggs!)

Used books can contain unwelcome pests like booklice, silverfish, and beetle larvae, which feed on mold, glue, and paper. Freezing books for at least 48 hours in sealed plastic bags can effectively kill these insects and their eggs. Freezing is a non-toxic, chemical-free way to kill pests at all life stages (eggs, larvae, and adults), by causing ice crystals to form inside insect cells, which ruptures them and kills the insect.

In fact, museums and archival institutions sometimes use deep freezing techniques (often for a week or longer at very low temps) to disinfect historical documents and rare books without using harsh chemicals.

Stop Mold Growth

Even if no pests are visible, freezing also halts mold growth, which is often what attracts bugs like booklice. So, it’s a two-for-one benefit: pest control and mold inhibition. Mold thrives in warm, humid environments and can be super damaging. Books are especially susceptible, as the paper is organic and porous, and the glue and bindings can provide more nutrients for mold to grow and spread. Common signs of moldy books include a musty or earthy smell, discoloration (especially black, white, green, or orange spots), soft or fuzzy patches on the cover or pages, and warped or wavy pages due to moisture. 

So how does freezing solve the problem? Mold spores become dormant at temperatures below freezing. Freezing also stops mold from producing enzymes and spreading across the pages or bindings. Like museums, Freezing is a non-invasive, preservation-friendly option used by libraries and archives to stabilize moldy books until they can be properly cleaned.

How to Freeze Books Safely

So, clearly there's good reason to be freezing our thrifted books when we bring them home, but there’s a right way to do it.

First, place the books in a zip-lock bag to prevent moisture from entering, and to keep everything (pages and pests) contained. Put the book in the freezer and keep it sealed for at least 48 hours, but preferably a week. When you’re ready to take it out, let it thaw slowly. Allow the book to come back to room temperature while still sealed to prevent condensation.