Efke coating facility - coating matrix film
Originally Posted by Photo Engineer
Here are some pictures I took at Fotokemika (Efke brand) while we were testing the new emulsion. There are pictures of the trough coater, the drying tunnel (first half) with the coating foreman (on left) and our customer rep. Also shown is the bull wheel which turns the corner, and the wind up station at the end. The drying tunnel is horseshoe shaped going out about 100 feet, around the bull wheel, and back to the windup station (Pictured with myself).
The trough coater picture shows a ultrasonic debubbling device on the wall. The emulsion is pumped through that, into the trough, and it overflows the trough continuously. The roller is lowered to the surface of the emulsion, and the web is started. Pictured is a rubberized cloth leader used for threading the coater. Up above is the chill station, and an over coater used for putting a hardening overcoat on - we didn't use this as the matrix film is unhardened. After that, a few people working on a cat walk gather the loops and attach them to clips on the overhead track. The loops travel slowly out to the the bullwheel, and then back to the windup station. Temperature and humidity are controlled along the way for ideal drying conditions as the film moves along.
I think they told me that the equipment was from Dupont, pre WWII. Fotokemika has a large 'campus' which was very busy during the soviet era, but has been greatly downsized more recently. It was a kick walking down long, long halls in the total darkness, and turning into a side room that you couldn't see which was very dimly lit with red safelights. Sort of like a halloween spook house, but without the suprises.
Also shown is a technician mixing the silver nitrate for the small test we ran, a vacuum filter, a large noodling press, and a sensitizing test. There is also a picture of a small mixer - used for precipitation during small tests such as we were doing. They had much larger temperature controlled mixing vessels. They had tubes running through the gelatin solution which controlled the temperature while precip was happening. They could match the temperature profile that I used while developing the formulation here in the US.
They would coat glass plates frequently while sensitizing, expose them while wet to a test pattern, and process them. They would run into the emulsion engineer's office with film boxes with the processed wet plates, and she would inspect it for a particular type of colored fog which indicated that the ideal sensitizing period had been exceeded.
It was a very interesting experience, and our Croatian hosts were very generous and entertained us by showing us around Zagreb. Samabor is a very nice small town about 1/2 hour out of Zagreb. We made 3 miles of matrix film, all of which has been sold. We had a good level of success partly because the techniques they used in production were similar to the techniques I used while developing the formulation. It translated to production quite well. Lots of dye prints are being made with this film these days.
Regards - Jim Browning