So you have bought a few Idriess books, maybe even splashed out on some first editions, and you are on the way to an Idriess collection (good luck and happy buying!). But having spent a bit (or a lot as the case may be), you will want to look after your valuable collection. Many sites give valuable advice about looking after collections. You may want to check these out:
These all give fairly similar and good advice: stack books upright firmly together but not too tight; avoid sunlight and temperature extremes and humidity; handle them carefully; dust them off and check for insects (silverfish, moths etc.) that may damage them; and cover them with a good quality, acid free cover. It is this last aspect of preservation I wish to look at in a little more detail.
The first thing I do when I get a new Idriess book (that is, new to me, but generally a first edition which may be over 90 years old) is to cover it. Most of the books arrive uncovered, except, if I'm lucky, some come with a dust jacket. Some arrive with a fairly ordinary attempt at a cover which I replace. A cover helps protect and preserve a book (the outside anyway) from bumps, knocks, scratches, smudges, and wear and tear. Dust jackets are particularly vulnerable. So, as the sun-cancer warning goes: "Cover-up!" Robert Muir of Robert Muir Books (I live in Perth) showed me a copy of his Cyaniding for Gold and told me he had quickly covered it in a good quality cover.
Now, you can buy ready made covers to suit a range of book sizes such as Brodart, which usually come with a paper backing and give excellent protection, especially for dust-covers. For myself I decided to go down the road of buying a roll of covering material and a roll of book tape: cheaper, but a bit more work. When covering books, the cardinal rule for collectors is not to stick any sticky-tape, etc., onto any part of a book (no doubt you have encountered Idriess books disfigured by tape as people have attempted crude repairs). So, the roll I bought was 50m x 300mm of Polypropylene (Prolene), 90 microns, from a library supplies place for under $60, which is well on the way to covering 100 books or so. This material is acid/phthalate/chlorine free and UV resistant. The 300mm width caters for all the three main sizes of Idriess editions (5" x 7 3/8" - 127mm x 187mm = most of the earlier editions; 5 1/2" x 8 1/4" - 140mm x 210mm = mostly later editions, from about 1941 on; and 6" x 9 1/4" - 153mm x 236mm = Our Stone Age Mystery and Our Living Stone Age) and can be trimmed if needed. The Book Tape is Scotch and is 13.7m x 38.1mm It is very sticky and acid-free (apparently!) and available from many places.
In my system of covering I cut 4 pieces of tape to hold the cover in place and only use it Prolene to Prolene, so my cover is not stuck to my book. I place the book on the spread out Prolene and fold in a flap at one end. Generally I use the same technique for a book with or without a DJ, or for a soft-cover (paperback). If it has a DJ, I allow enough Prolene to cover that also, allowing about a centimetre overlap over the flap. I use wooden pegs to hold the Prolene in place - it is nice, strong and supple material, but slippery! I measure the overlap on the end I've pegged, then flip the book to its other side and measure out the same distance. I fold that end in then peg that side too. Then I cut the Prolene to fit. I either cut a flap to fit in the spine or cut around the spine. I cut an angle off each corner. I cut off the bottom and top of the Prolene on the inside of the flap so it folds in easily and is not doubled up. With 2 pieces of tape I stick the top and bottom Prolene flaps to the end flap and the same for the other side. Remove the pegs and Voila! This system is not perfect - to remove the Prolene cover you have to peel off at least two of the tape pieces - but I find it effective. Occasionally with a very good DJ (usually a more modern, stronger one) I will just cover the DJ itself, creasing the Prolene top and bottom and folding in and taping the end flaps (not directly!). Here are some photos. Hope they help, and have fun covering and protecting your collection. As one spy said to the other: "Don't blow your cover!"