Quote Originally Posted by sandermarijn View Post
I have a box of MGIV filters and an older box of MGIII filters.
Correcting myself: I have two boxes of small MGIV (or perhaps MGIII, if those exist) filters and one box with larger MGII's.

The MGII's must be quite old (1980's?). I got them around ten years ago with an enlarger (Durst M800). These are the filters I currently use, though never above grade 3 or perhaps 3 1/2.

Compared to the newer smaller filters the higher grades (3 1/2 - 5) have discoloured quite a lot. Especially grade 4 has been affected- this one also looks a bit flaky if you look up close (not visible in this picture).

mg_filters_compared_ii.jpg

Grades 1 to 2 1/2 seem to have discoloured very little. Their colour is almost indiscernible from the best set. Fortunately I use these grades most; almost never the higher ones.

mg_filters_compared_i.jpg

Thanks for bringing this up Roger! I never realized until now that the higher grades degenerate.

I won't rush out to buy new ones, but if I want to use the higher grades some day I probably should. Pity that a 100 euro filter set only lasts 5-7 years (quoting Simon) in the highest grades. That said, Simon's estimate is probably on the conservative side (?), and 100 euros spread out over say 10 years is not all that much.

Is there any way to increase the filters' longevity, apart from storing them in a dry & dark place and handling with care? Freeze the filters you don't often use? Sounds a bit ridiculous but maybe it helps?

Sander