Agyrotype sensitizer shot?
I purchased a bottle of Agyrotype last spring from B&S. Used very little of it and it was originally working great. Six months later, I hadn't used any since first opening it and found that there appeared to be mold on the top (white blobs). I strained the sensitizer with a coffee filter to remove the mold. It also strained off a small amount of black sludge.
I've just made a test print with the sensitizer and the speed seems to have dropped considerably? I exposed for more than double what was my normal exposure time and it still wasn't close to enough (my normal is 60 units and exposed for 150) . I understand that the small amount of sludge was silver that precipitated out but I can't see how it would effect the exposure this much.
I thought that this sensitizer should last at least a year. It's been stored in a cool dark place.
is this the same as POP Collodion?? if so then the mixture will NOT keep as I well know...maybe B+S knows something I don't...
David, IME, with Vandyke and Argyrotype kind of sensitizers, it's best to use them up within 3-4 months; to be on the safe side, just mix and/or purchase the amount you're going to use up within 3-4 months. Also, the coffee filter that you used may have caused contamination; use specialized / laboratory grade filter papers for filtering chemistry to be safe. (OTOH, as a note: I haven't had any problems with "Melitta" brand coffee filters up to date...)
making my own Argyrotype sensitizer
I ended up purchasing sulphamic acid and silver oxide to make my own Argyrotype sensitizer.
It seemed to go well but I've ended up with a lot of sludge. I've filtered the sensitizer with two layers of unbleached coffee filters but the fine sediment still appears. After sitting a long period the sediment does fall and some light passes through the sensitizer (and brown bottle).
My first thought was that perhaps I didn't keep the sensitizer heated long enough while I was mixing in the FAC ( I recall taking off the heat while adding the silver oxide). So, I reheated it today to 60 degrees C. (as Dr. Ware recommends) and stirred for over an hour (I've got a magnetic stirrer & heater which is fantastic). Anyway, this didn't seem to make any difference, as I've just now re-filtered with the coffee filters and it still has sediment.
I have printed with this sensitizer (with sediment) and it works but the dmax seems a little inconsistent over the coated area.
So, I guess I need to get better lab grade filters as the coffee filters are not working? But where?
Inconsistent dmax sounds similar to my contaminated VDB experience. I had sediment in sensitizer and filtered it then had the similar problem.
Originally Posted by davido
Loris pointed out that it might be contamination problem, and I tried the coffee filter he recommended (melitta brand).
Since than I filtered 2 VDB and 1 New Cyanotype sensitizers with that filter brand, and no problems.
It is likely to be a contamination problem, but I have no experience with argyrotype.
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
Are you still getting sediment Herzelied? Even after filtering with the coffee filters, I'm still getting it. I think the sediment might be the problem? So, I'm going to get lab quality filters anyway. I'm not sure what grade to get though?
It's this whole other world, deciding what grade of filters i need if coffee filters aren't working.
After filtering VDB solution two or three times, I have no more sediments.
I have very clean bright yellow VDB sensitizer, it used to be quite murky and greenish with all the particles floating in it before filtering.
I can see through the brown bottle, it is definitely clear.
The coffee filter is working fine for me now.
I am sure someone would comment on the lab quality filters. I would like to know what to use too.