huehnerhose
Hi!
A while ago, I got hold of a few bags of old ORWO A300. These are 3.5-litre batches, two-component. I prepared it as described in the Calbe documentation for the A300. I also prepared the dilutions for paper in accordance with the Calbe documentation.
One of the bottles was sitting in my darkroom (under the roof) and got a bit cold... it had a nasty sediment... as I still have enough mixture left, I simply tipped the bottle away and made a fresh batch; I thought it was mainly down to the temperature.
Now the new batch has been sitting in the normal ‘living area’ for about two weeks, so always between 18°C and 23°C... now there’s sediment at the bottom again.
They’re these white crystals – just looks like some weird chemical stuff. What could be causing this? I don’t think the powders have ‘gone off’; they were just nice and dry, not clumpy, and white...
Any ideas?
Many thanks
Sebastian
cfb_de
Hello Sebastian,
That can happen with traditional fixing baths. They aren’t resistant to oxidation indefinitely, and they don’t take kindly to being prepared with (hard) tap water either.
What’s more, sulphur compounds in particular are known for their ability to provide a breeding ground for myriads of fungi and bacteria.
Apart from water, thiosulphate and sulphite, there’s simply nothing else in the classic solution for true fine printers (in other words: the cheap version from the 1890s).
Best regards,
Franz
huehnerhose
Hi Franz,
Sorry, but I’m not really making head nor tail of your reply. That it simply stops working – if it’s been sitting for a while – OK, but it’s just stopped working again after barely two weeks, and I don’t understand that. Or were you trying to say that the powders ‘age’ for the reasons you mentioned?
Regarding the water: As I generally have issues with the water here, I actually only use distilled water now. (No comments regarding the religious wars that were once waged over this *vague memory*) So, as far as I can tell, that shouldn’t be the problem.
But I’m sure you can tell me how hot you can heat these compounds before stirring them back in?
Regards
Sebastian
