"Golden Tetras" or Cubic Grains and the Tetradecahedral

[wildbillbugman]

Perhaps ther will be a giant Solar Flair and all the digital cameras on earth will be ruined. Then there will be a cripling shortage of bateries and digital cameras will be gone. Or even a nuclear explosion 400 miles above the earth.............................
Pleasant Dreams,
Bill

 

[wildbillbugman]

[ Of course, slow mixing will tend to create a greater mix of crystal types or even an unusable emulsion.

PE[/QUOTE]

PE,
Could you specify what about the emulsion made it "unusable"?
Bill

 

[keithwms]

The research will not be "lost".... it may not show up in a consumer film, but rest assured that there are plenty of folks very interested in the underlying photophysics.

 

[Photo Engineer]

Well, IDK when Mitchell's work took place, but Anabelle's work took place nearly 20 years ago. This is not untypical of Research, Development and Product release cycles. If you reconcile those dates, maybe Anabelle preceded Mitchell but I know it was unpublished.

PE

 

[wildbillbugman]

The research will not be "lost".... it may not show up in a consumer film, but rest assured that there are plenty of folks very interested in the underlying photophysics.

Keith,

That is the best news I have heared today. Perhaps there is room for "optimists" on this planet.
Bill

 

[Photo Engineer]

[ Of course, slow mixing will tend to create a greater mix of crystal types or even an unusable emulsion.

PE

PE,
Could you specify what about the emulsion made it "unusable"?
Bill[/QUOTE]

The above quotes are a bit garbled due to parsing, but....

Bad mixing will cause local hot spots which lead to something akin to pepper grain which is actually huge crystals that cannot be peptized by gelatin. This is known in the literature so I'm sorry that I didn't go into detail as I thought that it was known.

In any event, the emulsion has huge crystals that can be felt with the finger and are "crunchy". They give rise to lower contrast and big black blotches in the image.

PE

 

[wildbillbugman]

Yes PE,
Thank you for the clarification. I have seen this GRIT in some of my own emulsions. I have tried to filter out the grit with multiple gold mesh filtrations. But the subsequent emulsion still "sucked". I think that I will switch from magnetic stirring plates to overhead mixers, with hot-plate heated water baths under the emulsion. Buying used magnetic stirrers on Ebay is a real crapshoot. They often just do not have enough torque.
Bill

 

[Photo Engineer]

Bill;

In the range from 100 - 500 ml of emulsion, 300 RPM or higher (without stirring in bubbles) with a magnetic stirrer should work. If it does not, then the formula is off.

PE