Sensitizer in emulsion

[kevin klein]

I just made a 2oz. batch of emulsion (Ostermans emulsion) and forgot to add the very dilute sodiumthiosulfate sensitizer to the reserve gelatin. will this affect anything in a bad way? Althaough the instructions do not call for it, I was just wondering if it might also have an effect on controlling fog.

The urge to make dry tintypes hit again and the biggest problem had been fog in the shadow areas, I am trying to correct this.

 

[Gerald C Koch]

Many people working with alternative processes find that keeping a notebook can be very useful. Making a checklist can prevent this problem in the future. We all experience lapses in memory.

 

[Photo Engineer]

You can add the sensitizer later in the process, but if the emulsion is washed, the sensitization process is much faster. Best of luck on this one.

PE

 

[kevin klein]

The emulsion I just made has been washed in purified water instead of tap water. I tested the tap water and found that adding a little silver nitrate causes significant cloudiness, the purified water does not (reverse osmosis water from a dispenser in the grocery store). I also discovered a few small light leaks reflecting in the bottom of the washing sink from the cealing, a couple of nail holes and a gap about 8" long, although difused, and about a 1/8" wide directly above the washing area, that could also be a big Duuuhhhhh...cause, we'll see. I will divide the emulsion in to two parts, leave one with no additives and add hardner to the other, coat some small plates and put a penny on top and expose to light and develop. If there is still a problem, try one more time with the leak covered up.

 

[kevin klein]

Problem solved!!! It's the water! I washed the emulsion with purified water and it turned perfect, no sign of fog. I usedto wash the emulsion with tap water with no problem, now it does'nt work that way. The city upgraded the water plant 5 or 6 years ago and must have added a bunch of stuff to the water. Makes me wonder, I'm ingesting that stuff. I saw a city employee at the grocery store buying purified drinking water, Hmmmmmm...!

 

[Photo Engineer]

Fiver or 6 years? You should have seen this problem earlier!

But, GEH upgraded its water supply and we had a similar problem but different reasons. Any tiny change can cause fog to creep in on its little cat feet! (as they say)

PE

 

[kevin klein]

The last time I was fooling around with this positive stuff I did'nt try the purer water and I was making mostly negative emulsion wich did not show fog as much.