georg16nik
Allowing Ads
- Joined
- Aug 3, 2010
- Messages
- 1,101
- Format
- Multi Format
http://www.apug.org/forums/forum37/98227-making-most-rodinal.htmlIf you use Rodinal with 16°C, you can reach 1/3 ... 1/2 stop more and so coming closer to the bos speed. The reason may be that the developer has mor time to reach and develop the deeper emulsion parts.
The time is 1.6 times longer, that means 21 mins instead of 13.
> crystallisation ... is it normal?
Yes. Rodinal contains caustic potash. In contact with air the solution absorbs carbon dioxide which changes the caustic to potassium carbonate which is less soluble.
Thanks Uwe!
So, how can we deal with it?
Do we have to filter it out or it might be dilute upon warming up ? or something else or even none to do?
Thanks!
Where did you get this idea?The solubility of potassium carbonate is 112g per 100ml at 20 C.> crystallisation ... is it normal?
Yes. Rodinal contains caustic potash. In contact with air the solution absorbs carbon dioxide which changes the caustic to potassium carbonate which is less soluble.
I have noticed some crystallisation in Rodinal, is it normal? Any thoughts to get rid of those?
There is an expansion shock to the emulsion going from high pH (OH ion) to acid stop if you must use an acid stop with non prehardned film you need tight temperature control.Most of the issues with Rodinal are caused by poor technique, it contains free Hydroxide and this has a tendency to soften the emulsion of some films which are less hardened than most.
In Germany use of lower processing temperatures 16ºC - 18ºC are often advocated for the finest grain with Rodinal, this helps inhibit swelling of the emulsion. However in practice as long as you use tight control of your processing temperatures ensuring little to no variation you will achieve excellent results and very fine grain with medium and slower speed films.
Ian
I think it more likely that any crystals are from potassium aminophenolate being deposited from a superaturated solution as they may be found in bottles sealed off from the atmosphere.
HP5+ or Kentmere 400 may be better 1:100 20C full stand 50-60 minutes.
Your have exposed the sign which is in the shade.
- It may need bit more exposure to have certain brilliance.
- Remember Foma films builds contrast rather very fast, which is obvious in the case presented.
- Test all films with same scene and with similar lighting conditions.
Fomapan 200 is very good film.
Expose at E.I. 100 and develop 20% less with Rodinal.
Sent from my GT-I9301I using Tapatalk
Both are Harman products the Kentmere is cheaper normally about 2/3 in bulk.What's kentmere? I've heard it mentioned but it seems to have never been available in Australia.
Sent from my iPhone using Tapatalk
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?
We use cookies and similar technologies for the following purposes:
Do you accept cookies and these technologies?