SamuliSchielke
Does it contain the same ingredients as Agfa Sistan? (If I’m not mistaken, that would mainly be potassium rhodanide as a silver stabiliser and something else as a wetting agent)
Best regards,
Samuli
cfb_de
Sounds about right. Potassium rhodanide and a suitable surfactant. If Mirko had safety data sheets available for these (as he really should), then I could answer your question straight away.
Best regards,
Franz
MirkoBoeddecker
Hello Samuli,
Yes, that’s right. However, it’s in a different, more optimised concentration and with a few extra ingredients added.
When we started developing the product, we realised that our sample of another product (which was intended to replace it, as the manufacturer said it was being withdrawn from the market) wasn’t really effective.
Under xenon light, the images treated with the product actually faded faster than the untreated ones :unsure:
We therefore completely retested the optimal concentration of the active ingredient for ADOSTAB (visibly and measurably effective but with no tonal shift yet, determined by test series plus visual inspection under daylight followed by xenon irradiation).
The prints treated with ADOSTAB at the current concentration showed significantly better stability under long-term exposure to intense xenon light.
Product development took over a year and a half... partly due to the long-term tests.
We do not know why our sample of the other product performed so poorly. We suspect fluctuations in the quality of the raw materials (it wouldn’t be the first time recently).
However, we only had one bottle left as there was nothing else available to buy at that time (December 2005).
However, based on our tests, it would generally be possible to use a significantly higher concentration of this product without negatively affecting the image result, and this would certainly also result in significantly better effectiveness.
I’m writing all this because I’m curious to know what experiences you’ve had with image stabilisers.
Has anyone ever questioned or tested their effectiveness?
It would certainly be interesting to know whether the process itself needs to be constantly checked or whether, in principle, one can rely on its effectiveness.
That would, of course, apply equally to our product.
With selenium toner, you can see the tonal transition. It is clear when the chemical reaction has taken place and when it has not.
Best regards,
Mirko
cfb_de
Hello Mirko,
First of all: "Hats off!" to your excellent formulation regarding "2005", "product" and "no longer available"! It’s a real pleasure to read, and I mean that sincerely.
Regarding the question of monitoring the product: Yes, this may be necessary with rhodanide solutions. On the one hand, the quality of the raw material is actually subject to greater fluctuations when it comes to the purity grade “pro photo” or “technical” (i.e. a content of up to -20% is to be expected); on the other hand, the stuff is quite readily metabolised by our dear single-celled friends – so it goes rancid even whilst still in the sack in the production facilities’ storerooms.
It is only in combination with silver ions that it becomes toxic enough for these little critters to leave it alone, allowing the preservative effect for the photograph to take hold.
Before any uninformed readers start to panic: you can still touch the pictures. You can handle them without issue, and the bactericidal effect stems from the ‘natural’ silver in a perfectly ordinary black-and-white print. In the case of colour photographs, this was previously achieved using formalin (aka ‘Stabi-Bad’) due to the lack of silver; since this is no longer permitted (and for cost^H^H^H^H^H^Henvironmental reasons, a proper final rinse is also omitted), they no longer last.
Best regards,
Franz
SamuliSchielke
That’s brilliant! I’ll be including Adostab in my next order, especially as I’ve now run out of that other product I didn’t mention.
I’ve never actually tested whether the shelf life really is any better; I’ve just gone by the manufacturer’s claims – though I’ve only been soaking my prints in it for just over a year, so I doubt you’d notice the difference that quickly...
Best regards,
Samuli
