An “exploded booklet” is a philatelic term you may encounter. What is it? I’ll give you a hint; it has nothing to do with dynamite.
When booklet stamps first appeared in the late 1890s, they were assembled by stapling panes of stamps together between two cardboard covers. Many times, the booklets would have interleaving glassine paper to prevent the stamps from sticking together. Stapling booklets continued until the 1970s. Because the staple is firm, it is impossible to fully examine the contents without bending the booklet cover. And to many booklet collectors, a creased booklet cover is considered a damaged full booklet. Also, the staple may become rusty over time if it’s exposed to moisture. Rust colored stains on booklets are considered damaged booklets too.
An exploded booklet is when the staple has been carefully removed without damaging the covers or the contents. Sometimes, the original staple is kept with the entire booklet. This solves two problems. If the staple becomes rusty, the rust stain does not migrate to the booklet itself. And with the staple removed, the panes can be easily disassembled to check the condition of the gum, the centering of the perforations, and so forth.
In the 1970s, the USPS moved to producing booklets where the stamps are attached with a gummed tab to the booklet cover. And in the 1990s, the USPS moved to booklets with no cardboard covers – just panes of stamps where strips of selvedge could be removed allowing customers to fold the panes into a smaller size. Eliminating booklet covers reduced production costs.
Modern panes are much easier to examine. There is no staple to remove. To fully examine the early US booklet panes, you need to remove the staple to allow the booklet to fully open up – thus “exploding” the booklet into its individual pieces.