Obsidian Aqua

[Andrew O'Neill]

Finally got around to checking out this staining developer by Jay DeFehr.

 

[Rick A]

Thank you for that video Andy. I had considered OA for deep tank developing my LF films in frames, but have abandoned that idea. I still like the idea and probably will try it with rotary developing sheet film.

 

[revdoc]

I've tried it, and it gave excellent results with Aviphot 80. The downside is that it doesn't last long... typically only a few months. When it dies, it turns bright green when it hits the carbonate solution.

I've since switched to hypercat, which is chemically very similar, but will hopefully have a longer shelf life.

 

[Trask]

Thank you very much for making these tests and putting together this video -- it encourages me to take another whack at it. I started using OA back around 2014, and found it a sometimes maddening developer -- it often did not come close to meeting the nominal film speed, seeming to demand significant additional exposure. In one instance, the emulsion fell off in strips. But at other times, it came across with negatives that could produce nice images (IMHO) -- see attachments. I have always thought that OA is very sensitive to any hint of contamination or improper handling/technique. I don't feel it's a do-all sort of developer like Microdot or D-76, which are flexible via dilution etc. You have to meet OA on its own terms -- if you do, and the OA is feeling nice that day, some good images can result.

 

[Andrew O'Neill]

I've tried it, and it gave excellent results with Aviphot 80. The downside is that it doesn't last long... typically only a few months. When it dies, it turns bright green when it hits the carbonate solution.

I've since switched to hypercat, which is chemically very similar, but will hopefully have a longer shelf life.

That's good to know! Thank you!

 

[Andrew O'Neill]

Thank you very much for making these tests and putting together this video -- it encourages me to take another whack at it. I started using OA back around 2014, and found it a sometimes maddening developer -- it often did not come close to meeting the nominal film speed, seeming to demand significant additional exposure. In one instance, the emulsion fell off in strips. But at other times, it came across with negatives that could produce nice images (IMHO) -- see attachments. I have always thought that OA is very sensitive to any hint of contamination or improper handling/technique. I don't feel it's a do-all sort of developer like Microdot or D-76, which are flexible via dilution etc. You have to meet OA on its own terms -- if you do, and the OA is feeling nice that day, some good images can result.

I've been out in the field a few more times since completing the video, and it appears that you do lose some speed with OA. I'll have to do some more testing... Thank you for commenting!

 

[JensH]

Dear Andrew,

very interesting video.
I had great results with FP4+ and a similar Pyrocat developer (Windisch Compensating)...
HP5+ sometimes didn't build up highlights enorgh, so the standard mix isn't ideal here.

Best
Jens