For those following me on Facebook might have seen a post on issues with specks on the plates. It took me quite some time to figure out what it is exactly. I have looked at several options. But it really took ages, at least to me, to narrow it down.
Specks, appearing as little black dots, on the plates (see cropped image above). Not immediately, some plates needed a couple of hours, some took days to show. At first I thought of the silver nitrate bath. I had this before and boiling the bath down solved it back then. Not this time..
I rinse my plates, certainly in studio, for over half an hour. Specks.
I started to use freshly mixed fix before each shoot. Specks.
Collodion bottle was steady before using, no shaking. Specks.
Oeff…nutty specks…the thing I did notice was that the fixer bath upon every mix started to look dirtier and dirtier. I bought the Sodium Thiosulphate crystals, I believe, in 2011. 25 kilos at once; better be prepped I figured 🙂 I guess it’s prone to deteriorate over time. I decided to filter it, to the max. A lot of small stuff got filtered out, and the fixer turned out to be the problem! After filtering I was left with a clean fixer bath. No specks!
For the filtering I used a normal cotton pad to wipe of make-up. I pressed it firmly into the funnel (see above image), takes ages to filter a liter but it works!
Yihaa!
Photography Contrastique - Alternative Photographic Processes 
Next time, try a coffeefilter… I used to use fir other processes and it worked fine.
CU
C.
Thanks for the heads-up, will try!