Obsidian Aqua developer... baby!

[Gerald C Koch]

Catechol developers were popular during the 1930's and 40's particularly in Gernany. Catechol is a member of a small subset of developing agents that can be used alone to obtain continuous tone negatives. As a developing agent it requires a high pH using either a carbonate or even a hydroxide to work. While catechol is an isomer of hydroquinone it is more toxic. When using it or its solutions use nitrile rubber gloves. It also has a measureable vapor pressure at room temperature. So when measuring out the powder have good ventilation and avoid any spillage.

 

[Regular Rod]

Catechol developers were popular during the 1930's and 40's particularly in Gernany. Catechol is a member of a small subset of developing agents that can be used alone to obtain continuous tone negatives. As a developing agent it requires a high pH using either a carbonate or even a hydroxide to work. While catechol is an isomer of hydroquinone it is more toxic. When using it or its solutions use nitrile rubber gloves. It also has a measureable vapor pressure at room temperature. So when measuring out the powder have good ventilation and avoid any spillage.

+1 Worth the care needed though...

RR

 

[SchwinnParamount]

Yeah, I was wearing rubber gloves while developing film with the stuff. When mixing the A solution, I was amazed that the catechol flakes gave off such an odor while still dry. If I wasn't careful before getting a whiff, I sure was later. It's too late for me though, I've already grown a third thumb on my left hand.

 

[SchwinnParamount]

8 more Tri-X 4x5 negatives developed tonight. Exposed at 250asa. Dev 14m 1:1:500. Agitation 30 seconds, 30 seconds every 4 minutes. 70 degrees. They look nice. I'll scan tonight and print from them tomorrow. Maybe these will be good enough to post?

 

[SchwinnParamount]

One of the 4x5 films from Portland, developed in Obsidian Aqua. You can definitely see the edge effects on the emulsion side when you hold the negative oblique to the light. I don't know if they show up in the scan though.