|Some films with cubic grained emulsions|
These are important questions for New55 FILM. Polaroid used a material known as SO-139 for T55, supplied by Kodak. We know today that SO-139 is a dye sensitized cubic grained medium speed emulsion similar to Kodak's Panatomic-X, supplied in long rolls for processing.
One of the problems with old T55 was that the negative was too big: It's size was a poor fit in many scanner and enlarger carriers. We want to avoid that.
Another problem with custom made anything is lead time and start up cost. Could be too much in our case.
A better way is to find, if possible, something already available that works well. For those of you who have been following along, we started with EFKE because their film worked great in the DTR process, and we were quite disappointed when EFKE ceased production. I really liked it for everything: monobaths, DTR and conventional processing, but I had to get over it. Since that time we have purchased and done experiments with nearly every available black and white 4x5 film, and we have learned a lot of interesting and valuable things about them.
|Most of the cubes are near the surface, |
and that's good.
In the days when DTR was invented and developed by Agfa, and Polaroid, the only emulsions used were so-called cubic-grained emulsions. A cubic grained emulsion is, as the name implies, composed of silver halide grains shaped like cubes of salt, though smaller, often suspended in just a single layer of gelatin. Tri-X is a good example of a cubic grained emulsion. It can look sharp, and grainy too.
|The "tabs" are well below the surface.|
Fujifim and others do a much neater
job than this picture shows.
|The flat plates need to lay flat on the film base|
and this requires special coating tricks.
Instant photography utilizes the rapid processing of the negative and formation of the positive image. This process is slowed down by multilayered tab films, and they are not what we want right now for our New55 FILM negative.
We want the "rocks" to sit right next to our processing reagent and be available as quickly as possible so that the DTR process can proceed without delay. If you take a look at Fujifilm's FP-3000b negative, (out of production) which processes in 15 seconds, you can see the remaining silver grains with the naked eye!
Only one of Land's list of cubic grained emulsion films survives today. Note that he also experimented with papers, such as Kodabromide, as the "negative".
|Land's list of films tried. In those |
days they were all cubic
grained films and papers.
In some respects, the cubic grained emulsions we need for New55 FILM production are simpler and more widely known than our receiver sheet! Sobering, but also intriguing: Could we make film, too? If we want to do that, as a strategic move, where would we start? It's too soon for all that, as we are very busy with all the other things - items that are no longer made.
So we can be grateful for the likes of our existing film makers who have kept at least a few traditional emulsions alive and available, and we have learned that, in total, more cubic-grained emulsions are sold today than tab grain emulsions.
The final emulsion for New55 FILM production has NOT been set. That gives us some lateral maneuvering room as we plan the other parts of the system such as the processing chemicals, and the all-important receiver sheet design. You can be fairly certain, however, that any film we use will feature a cubic-grained emulsion.