Most people think "food" when they hear "freeze-drying."
But freeze-drying has practical applications that are useful to librarians.Robert Espinosa, preservation librarian at Brigham Young University's Harold B. Lee Library, uses freeze-drying to save books and other library materials from water and insect damage.
"When books are frozen, the water in them turns to ice crystals. Then, when you lower the pressure, the ice changes to a gas without going to a liquid," Espinosa said. This process is called sublimation.
It is like freezer burn, Espinosa said. Freezer burn occurs when something has been frozen too long. Because the environment in a freezer is cold and dry, moisture is eventually lost from the food. Freeze-drying is essentially the same thing, only much faster, because trying to completely dehydrate something in a normal freezer could take years.
Espinosa also said freeze-drying protects pages from becoming wrinkled and distorted and keeps mold from forming. After an accident when books get wet, the books are immediately frozen in a normal freezer to keep mold from growing and to keep the water from doing more damage. Then, when librarians have time, they take the books to a place where they can freeze-dry them.
Time is what librarians need the most, Espinosa said, because mold can begin growing on wet books within 48 hours.
Danny Merrill, owner of Madcat Merrill, a freeze-drying business in Logan, said the time it takes to completely freeze-dry a book depends upon how wet it is, but it can take weeks.
In the case of exterminating bugs, the whole freeze-drying process can be finished in about a day.
Rather than using pesticides, which could damage a book or even harm someone using the book, Merrill said exterminating bugs and insects through freeze-drying is a safe and effective way to protect a book from insect infestations.
Biscuit beetles, dry-wood termites and silverfish are among the most common book-destroying insects.
Many bugs can be killed with freezing alone, Espinosa said, but freeze-drying is an even more effective method of extermination.
"Freeze-drying works because it first freezes the bugs and then sucks all the water out of them," he said.
Whether treating for water damage or exterminating bugs, Merrill said, it is important to know how to treat a book after it comes out of a freeze-drier. Because freeze-drying draws all of the moisture out of a book, the book must have time to reabsorb moisture before it is handled.