Text block sag and what you can do about it

With another news-starved week of releases in the rearview mirror, let's fill the void by talking about something else related to books and collecting. The Civil War literature has its share of behemoths, and I'm certainly not alone in wanting to keep the most valuable books in the collection in the best shape possible. So many things make this difficult (among them the fact that few shippers make an effort to properly package a book anymore), but the hindering factor under discussion here will be text (a.k.a. page or book) block sag. That is when the gravitational weight of a shelved book's pages collectively pull downward on the binding, eventually forming the infamous smile-shaped droop to the text block's lower-corner, the edge of which then drags on the shelf bottom leading to unwanted applications of grime and wear. Just how much the block visibly pulls away from the spine head (forming a kind of tunnel between the spine face and text block backing) can be random. Anyone who stores their books in the classic upright position will come across this annoyance. Though some presumably vulnerable titles seem to miraculously escape the phenomenon, essentially every very thick book with modern binding will get it to some degree. Beyond being unsightly, the deformation, when severe, can certainly have a negative affect on a book's value and overall binding stability.

So what can you do about it?

(Option 1): Do nothing. If the affected book doesn't have much value or you never plan on selling it, you can just let it happen gracefully and worry about more important things.

(Option 2): Store your thickest books spine-down. This is a big no-no. Though it might seem like a reasonable preventative measure, the consensus among experts on modern binding techniques is that spine-down storage places undue pressure on all the wrong places.

(Option 3): Store books upright but very tightly pressed together. Theoretically, these horizontal forces will counteract, at least to some degree, the downward force created by the text block. This is another big no-no. Shelving books in this manner will over time result in damaging wear and can even cause harmful sticking between adjacent covers. Also, if books shelved this way have different heights, the covers will warp each other over time.

(Option 4): Flip the spines over occasionally, with the idea that the 'counter-sag' effect will tend to bring things well enough into realignment. I came to this solution independently for my mid-sized saggers. Though not ideal, from what I've read it seems to be an acceptable practice among bibliophiles. I find that it works pretty good on most offenders.

(Option 5): Fashion custom-sized support blocks. This is one in the category of too extreme for most, but I've read that some rare book collectors will make rectangular blocks (covered with acid-free material, of course) precisely measured to fit between front and back boards and slid underneath the text block to carry its weight.

(Option 6): Stack these kinds of books horizontally. This is the ideal solution; but, if you own a very large collection and have limited storage capacity, it's entirely impractical in terms of how much space it uses. Depending on the weight, you are limited to two or three additional books in the stack. That's a lot of wasted square footage.

So what do I do? For the most valuable big doorstoppers I try to find some place for horizontal storage. For the rest, I do a combination of #4 and reasonably (not too) tight shelving. If you have any advice on the topic or just think I'm insane to even care about such things, feel free to comment below.