And thank you Ken for recognizing it. I sometimes forget to
thank people. Not bad manners so much as more forgetfulness.
On 10/15/2021 1:49 PM, Ken Hart wrote:
Sabbatier effect?
"The Sabattier effect, also known as pseudo-solarization, is a phenomenon in photography in which the image recorded on a negative or on a photographic print is wholly or partially reversed in tone. Dark areas appear light or light areas appear dark. Solarization and pseudo-solarization are quite distinct effects." Wikipedia <https://en.wikipedia.org/wiki/Sabattier_effect>
I could easily be wrong. I've been wrong before, so I know what it feels like!
Ken Hart
kwhart1@xxxxxxxxxxxxxxx
On 10/15/21 4:02 PM, `Richard Knoppow wrote:
My memory is not what it used to be so I don't remember details. You may know there is an effect where if an emulsion is seriously overexposed it reverses the image. This effect was used to make direct positive material. I am pretty sure Kodak and others made such films for either document copying or for making duplicate negatives or duplicate release prints where only the original positive was availabe (or from a reversal film). I am just drawing blanks on the name of the material or even the name of the effect it made use of. I am hoping someone else here has enough of a clue to remember. Meanwhile I will look at what documentation I have to get a reminder. ISO-4 is in the range of fast enlarging paper or positive films. If you developed a clip what did you get? If I am right it should have come out black and a clip exposed to strong light should come out clear.
It is the term "direct positive" that leads me to think it might be this stuff. If, however, its just "positive" its probably something like Kodak Fine Grain Release Positive, a film originally intended to make release prints of B&W movies. This is a very slow film, ISO-4 would make sense for it, with an emulsion similar to fast printing paper like the late, lamented, Kodabromide. There is likely still data on it on line and similar film may still be made because it was also used to make masks (or matts) for motion picture special effects and titles. It can be processed in any fairly active developer like paper developer or D-19.
On 10/15/2021 12:38 PM, Martin magid wrote:
I developed a strip, and there is nothing printed on the edges.
Now what?
Marty