[Alt-photo] Re: DAS

[Kees Brandenburg]

On 17 apr. 2013, at 11:43, Loris Medici <mail at loris.medici.name> wrote:

> Wow, great info. Thanks very much! Doesn't sound too difficult; are
> those clearing solutions harmless in terms of longevity in some way?

Ultrastable is consired 'ultrastable' in terms of longevity. So I would say it does not harm. The permanganate in the clearing bath is a strong oxidizer but it is used very dilute here:  1 liter of the the working solution contains only 0,3 gram potassium permanganate, this makes a 0.03% solution! Handling the powder should be done very carefully though!

Maybe there are some ultrastable users from the past on the list that could chime in?
 
> BTW, what can you say about 6% sensitizer per gram of gelatin? My aim
> is to pour a thick but lightly pigmented tissue for high relief...

That's what I use. I also tried cutting down this percentage and used 4% too. Actually I did that by accident once. Lower concentrations yield a somewhat higher contrast at a lower sensitivity. As expected, and also known from dichromates.

Concerning drying in very dim daylight: I would avoid any daylight. It's just a guess but I could imagine that when drying for a very long time in a dim room with a little bit daylight might fog. This should be tested though! It presumes some sort of build up of very long exposure. But It could also be possible that if actinic light levels stays under a certain level nothing will happen.

regards,

Kees