Let's focus on a few topics for pure ultra-nerd excitement:
1) Advantages of flat storage of larger paper documents (=how to position your CGC books)
2) Why an airtight environment is optimal for CGC books (=should I put my CGC books in airtight bags?)
3) Recommendations for humidity and temperature levels (=what environment is good for CGC books?)
1. Flat storage.
Regarding the flat storage of larger paper documents, (and I consider magazines and smaller comic books belonging to this category,) I found this interesting description:
"Just where exactly the belief originated that comic books are subject to less stress when stored upright and will inevitably show spine rolling if kept flat is hard to tell, but in all probability this point of view goes back to the era of pre-conservation consciousness when comic books were kept in the loose stacks mentioned at the outset. In such circumstances (for instance with large piles or comics of different sizes and weight) the fact that the spine side is thicker (accentuated by the two staples used to hold the comic book together) can create a lopsided U which will eventually roll the indivdiual comics into the same shape (hence the term "spine rolling"). There is, however, ample and informed information available which dispells the myth of the absolute imperative for vertical storage.
The Northeast Document Conservation Center (a non-profit regional conservation center in the United States, founded in 1973 and counting amongst its clients the Boston Public Library and Harvard University) advised that although vertical storage in office files or in upright flip-top archival document storage boxes is acceptable for legal-sized or smaller documents, any objects larger than 15" x 9" should be stored flat. This is due to the pull forces which documents stored in an upright position are subject to, and it is safe to assume that what is best practice for larger size documents works out well for comic books as well."
Source: http://www.panelology.info/StoringComics.html
Thus flat storage, where the forces of gravity have minimal impact on the book corners, may be a preferred storage method for CGC books (although to my knowledge no experiment has been performed to examine, how many years of storage it may take to favor flat to upright storage ;-)
2. Airtight environment.
Mylar bags may help to keep an airtight environment for our dear magazines. According to E. Gerber, one of the leading manufacturers of Mylar (ok, his potential inhability may be a small issue), it seems that airtight encapsulation is preferred:
"Isn't it bad to completely seal off the comics and make them airtight? The reality is that an airtight environment is the proper environment and by far the best one for preservation. By keeping out the oxygen, moisture and insects, and by keeping the temperature reasonably low, you can provide an environment in which your comics will become "Golden." For example, go to any library that has older volumes. Open any book and figure out why the pages are always browner at the edges and get lighter and whiter as you move towards the middle of the page. The inside of that book has not been in contact with any moisture, fresh re-circulating oxygen or light".
Source: http://www.egerber.com/aboutpreservation2.asp
But then again, this may be not big issue with CGC books. The American chemist Max Rodel investigated a few of his CGC books by testing these for water and air influx, he concluded:
"CGC's holders are both air-tight and water-tight. This is because the CGC "holder" is actually two holders, one inside the other. The outer holder that you actually touch is merely a hard protective shell. The comic book inside actually is completely sealed within an inner holder that is made from a clear, softer, flexible kind of plastic. This inner holder is independent from the hard, protective outer shell. The inner holder is sealed air- and water-tight on all four sides. So CGC'd books are completely protected from all moisture and oxygen, forever!
The CGC label is not sealed within the inner holder, but free-floats inside the outer shell. If you crack open the outer shell, the label can fall out. The outer shell is not air-tight, so one minor drawback of CGC's system is that, in the unfortunate event of flood or any water immersion, the comic book itself would be protected but the label would get wet. (CGC's competitor, PGX, has solved this potential problem by sealing the label inside the inner holder with the comic. This permanently attaches the label it to the comic book and, in my opinion, is a better system.
Perhaps you knew all this already, but I thought I would pass on things I've learned by breaking comics out of their holders to see how they were put together".
Putting CGC books in Mylar bags do make them quite pretty to look at -- and you may strengthen the holder and keep it free from scratches this way. Special Mylar bags for CGC books (including magazines) may be found at EBay.
3. Temperature, light and humidity recommendations.
Temperature and humidity levels for proper CGC book storage should be about 18 degrees Celsius and about 30 to 40% relative humidity (better safe than sorry even with the Mylar). And of course the books should not be exposed to UV light - I try to treat mine as vampires, no direct sunlight! ;-)
"The optimal temperature for books is 65° Fahrenheit (18° Celsius) with a relative humidity of 40%. This may be hard to achieve in hot Florida summers. Stability is most important. A good rule of thumb is, if you are hot and sticky, your books are, too. [...] Books are best stored in the dark, or at least out of direct sunlight."
Source: http://dlis.dos.state.fl.us/archives/preservation/books/index.cfm
Again, since the inner Barex bags seem airtight, humidity may not be much of an issue - but temperature fluctuations will be a problem. The main problem with temperature fluctuations is that this causes different materials to expand or shrink with different gradients (=material's coefficient of thermal expansion). So the ink on the cover of CGC book may expand differently than the paper it is printed on. Thus many years of temperature fluctuations cause faster deterioration:
"Extensive research and a wealth of accumulated evidence show that the lower the temperature at which it is stored, the longer paper will last. It can be demonstrated theoretically that for every 10°F decrease in temperature, the useful life of paper is approximately doubled. As a result, a number of modern research libraries and archives have been designed with storage areas in which the temperature can be maintained as low as 55°F (=13°C). Few, if any, private homes or small libraries would find such a low temperature feasible or acceptable, but the principle is sound -- the lower the storage temperature the longer the paper will endure, all other factors being equal. For most homes and libraries practical considerations dictate a temperature range of 68° to 75°F (=20° to 24°C).
Source: http://www.southalabama.edu/archives/html/guide/bookcare.htm
Furthermore, ideally books should rarely be exposed to light:
"Materials degrade more quickly when exposed to light, especially ultraviolet (UV). Surprisingly, fluorescent tubes often emit a relatively high level of UV. Lighting should be turned on only when it is needed. Ideally, storage areas should have no windows. Where windows are present, they should be covered with opaque curtains or blinds."
Source: http://www.naa.gov.au/records-management/agency/preserve/physical-preservation/artworks.aspx
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