by Craig Stark

#5, 10 November 2003

Are You Cooking The Books?

The internet, as most of us know, is an extraordinary font of information that's both instantly accessible and seemingly boundless in scope and depth. However, as most of us also know, it can be an equally boundless font of misinformation. Misinformation about books is no exception.

One class of misinformation that's been surprisingly durable - in fact, annoyingly persistent - over the years pertains to the so-called beneficial effects of microwaving books. It's difficult to say why. Part of this may have to do with the almost overwhelming temptation some of us have to experiment with devices that are readily available in almost any home and, in turn, to triumphantly declare success on the basis of a woefully small sampling. We had the unfortunate "good" luck to successfully repair a rolled spine on a paperback once using a microwave treatment, unfortunate because it was the first one we'd ever tried to repair with this method. Naturally we'd thought we'd hit a home run on our first AB, something we could readily duplicate. Several later attempts, however, proved disastrous, and this was doubly unfortunate in the sense that we'd already recommended the procedure to others, thereby perpetuating the misinformation.

Part of the longevity of this misinformation may also have to do with the fact that a small body of scientific literature exists that supports the use of microwaves for various archival purposes, books included. The problem with this literature isn't that it's wrong; it's that it recommends a procedure that's both tightly controlled and somewhat complex - that is, duplicating it with household microwaves, which are all over the map in intensity, frequency, and distribution of radiation, would be effectively impossible without extensive experimentation, and even then the benefits might only be marginal and/or applicable to a small category of problems. The attempt to formulate a protocol that would apply in any universal sense would, in our opinion, be a fool's errand, and that's not even taking into account the almost endless variety of materials and corresponding adjustments that would be involved.

Anyway, let's take a closer look at some of these so-called beneficial effects.

  1. Microwaves kill active mildew or mold (and some would claim spores), thus eliminating book odor.

    There's no evidence we know of that microwaves will kill spores, though clearly they will kill active mold, since water is present. The problem is, the temperatures required to accomplish this are in the same range that cellulose degradation commences. Given also that microwaves heat books unevenly, especially thicker volumes, this becomes a disaster waiting to happen. (See list of additional risk factors below.)

  2. Microwaves kill insects (silverfish, book lice, etc.).

    Indeed, microwaves will kill insects, effectively boiling them alive, but again, temperatures required to accomplish this bring into play the same set of potential problems noted above. (Again, see list of additional risk factors below.)

  3. Microwaves re-melt binding glue, allowing for the reattachment of detached pages on paperbacks or the re-alignment of rolled spines.

    Microwaves most definitely will re-melt thermoplastic glues (i.e., specifically those glues which become fluid with the application of heat and harden at room temperature), but not all paperbacks are bound with thermoplastic glues. If you're a chemist, this might not be a problem; if not, watch out. Non-thermoplastic glues may literally crumble with the application of microwave heat; at best they'll become brittle. Note also that the thermoplastic glues themselves may not be at all accommodating. Several of our own disastrous attempts to repair books with thermoplastic bindings resulted in complete dis-binding after the glue had re-hardened. We have no idea why the glue had lost its adhesive oomph, but perhaps it had something to do with a previously existing state of degradation.

  4. Microwaves are effective in drying out wet books.

    There's been much experimentation with this but only limited success. If heating is uneven - an almost inevitable outcome with thicker books - damage to the extremities of a book is likely to occur before drying so much as begins on interior portions. To some extent this can be mitigated by fanning the book open, but then there will likely be aggravated problems with wrinkling of pages and warping of boards. Methods have been suggested to overcome these difficulties as well, but they are frequently so labor intensive or unpredictable as to make the process impractical. Far better to dry wet books in a frostless freezer (protected in freezer bags), especially since this also immediately arrests the growth of mold.

Additional Risk Factors

Metal is perhaps more frequently present in books than some of us might imagine, and we're all too familiar with the fate of metal in a microwave oven. Apart from the obvious presence of staples, paper clips, steel spiral bindings, gilt decorative elements, and so on, there are occasionally other metal components in bindings that may not be visible. Even more troubling are small iron fragments often found in 19th-century paper, especially paper with rag content. Cast iron machinery was frequently used to process raw materials a hundred or more years ago, and iron fragments were just as frequently introduced into fabrics - and subsequently paper used for book production.

Whatever form metal takes, consequences are usually dramatic. Zap paper with significant iron content, and almost instantaneous scorching occurs. Arcing will usually occur if staples or large pieces of metal are present, which could result in actual ignition of the book. Over-cooking any book, whether there's metal present or not, can result in scorching as well, not to mention irreversible cellulose damage.

In summary, a few marginal, though often unpredictable benefits can sometimes be achieved using a microwave oven, but since there are alternative methods available that have proven to be safe and effective, why take the risk? For those not familiar with these methods, look for detailed discussions of them in upcoming issues of the BookThinker.