I made the mistake today of starting down the rabbit hole of duplicating research I did a couple of years back on whether or not leather binocular cases are a good place to store the binoculars.
As I accumulated a lengthening list of classics, I noted that beautiful looking, externally, binoculars that have been carefully stored for decades in leather cases had a much higher incidence of prism fogging and fungus infestation. With particularly bad ones the cases also freaked of mold, but not always.
Somewhere along the way it struck me that my father's 1951 6x30 Steinheils (great binos incidentally, for their era) have not seen a case since the 1960s or so, and while they showed heavy honest where they had no trace of fogging or infestation.
When trying to pick up a pair of multicoated late DDR CZJ Delltrintems, I found it nearly all the ones coming in from the UK, carefully stored in cases in a damp country with little home AC, had fogging or infestation issues, and it took some time to find ones in the United States that were guaranteed to be crystal clear.
Unfortunately, many non astro folks store binoculars out in garages that are non-air-conditioned and poorly ventilated.
While researching my first B&L WWII binoculars and the government publications regarding servicing I also happened upon period publications indicating that the molding of binoculars while still in cases and wooden shipping boxes during World war II had been researched, and the cases had been blamed for the problem.
Of course I did not keep a copy, so I redid this today, and I think it is of general interest to collectors.
I have been storing my binoculars out of their cases with the cases stored separately, although Arizona is unlikely to be a place where problems might develop, but we do get our monsoon season, so better safe than sorry.
Here is much of what I found (and placed in an obscure thread)
I located a 1946 Nature paper that (comment unattributed) noted that
"... new instruments awaiting issue in depots were found to be rapidly deteriorating on the shelves due to fungal attack. In fact, instruments in store were more affected than those in use, and the trouble was greatest when they were housed in leather cases and stored in wooden boxes." p469
TURNER, J. S.; MCLENNAN, E. I.; ROGERS, J. S.; MATTHAEI, E. (1946). Tropic-Proofing of Optical Instruments by a Fungicide. Nature, 158(4014), 469–472. doi:10.1038/158469b0
Obviously a month in the tropics is the worst scenario, but many of our collector binoculars have sat for years in on the air conditioned houses, closets, or even boats (boat storage fogged and diminished a lovely Zeiss marine pair kept onboard a family friends cabin cruiser).
Looking for earlier, direct , material I found a once-classified 1944 document
Fungi and Tropical Deterioration: A Manual
By Selman Abraham Waksman, 1944 O.S.R. Report #4101, N.D.R.C., O.S.R.C.
available from Google Books (sorry if I'm not check my citation format)
See p 9:
"Leather cases and straps , unless fungus - proofed , offer
abundant opportunity for the development of fungi . The relative
ly high humidity inside cases and chests favors extensive fungus
growth and sporulation , that serve thus to contaminate the bi
noculars . Mites feeding upon the fungi as well as predatory
mites feeding on the fungus eating forms may contribute to the
infestation of the instrument with fungus spores . The entry of
these mites into instruments is common and the problem of whether
mites are responsible for carrying the fungus spores or whether
they follow the fungus mycelium feeding upon it has attracted
considerable attention . Mites are found readily wherever fungi
occur and the conclusion reached by Canadian investigators was
that " although they tend to aggravate the trouble , they can
hardly be blamed to any greater extent . "
The Australian report referenced is in the citations but was not directly available:
"Australian Report on the conditions of service materials under tropical conditions in New Guinea".
So I'll be keeping my classics apart from those lovely 50s and 60s leather cases (those German ones are so nice, too. Unfortunately.
But I'll use the cases when I travel or have them out for a while.
Edited by markb, 19 September 2021 - 12:35 AM.