The best way to store lenses long term? Vacuum seal?

[Bob Salomon]

I have a bunch of late 1980s Zeiss Jena Tessars (50 to 360mm) still unused in their original plastic bag inside the original cardboard box... I haven't noticed any haze, but maybe I should check gain. But they are not in a shutter, of course.

For what it’s worth, from when we were Gepe:
1 - Sometimes it appears that the glasses, mostly on older mounts, have a grey coating. Why is this and how can I clean the glass?
The grey coating you see on the glass is probably calcium-carbonate crystals emerging from a chemical reaction between the carbon-dioxide (CO2) in the air and the Calcium (Ca) in the glass. This can sometimes be seen as a grey haze on the surface of the glass.
It is a phenomenon that occurs with all glass materials, from the finest wineglasses on the shelf at home to normal windowpanes. After a period of time a grey surface appears which naturally has to be washed off to become clean again.
This problem is known among all glass manufacturers and they are, of course, trying to find a permanent solution to it, but so far they have only managed to delay the reaction.
It is difficult to determine how long a period of time it is before this greyish surface occurs, however, it is important to store the slide mounts in stable conditions, preferably dry and at a constant temperature. However, these crystals are not dangerous or harmful to the slide film, as it remains on the glass and does not transfer to the film.
A recommended method of cleaning glass slide mounts is to use a liquid lens cleaner and a smooth lens cleaning cloth.

[Tin Can]

The only lens I have that has changed while in my possession is a 790mm Reinhold, it is now 5.5 years old and has had OE caps on it always except when shooting.

Never in a bag or box and stored with my other LF.

It has a distinct dull haze coating now. I don't know if it is a glass or plastic optic so haven't attempted any cleaning.

The tube is PVC pipe. One cap is paperboard and the other grey plastic.

[Andre Noble]

A Mamiya lens tech once told me air flow is very important. I also us a small Germ Guardian UV sanitizer in my storage space that runs daily on a timer. I am blessed to live in year round arid climate.