Quote Originally Posted by Gerald Koch
It would be easy to determine by taking a piece of the film leader and looking at it. Rem-Jet would be a definite black. I've processed such film and waited until the end of processing to remove the coating using a sponge. The coating material decomposes in alkaline solutions leaving only finely divided carbon. The is nothing to gum up tanks or reels just wash everthing thoroughly.

Kodak PB-2 to remove Rem-Jet coating.

Distilled water (50C) .......................................... 750 ml
Borax (deca) .................................................. ... 20.0 g
Sodium sulfate .................................................. . 100 g
Sodium hydroxide ............................................... 1.0 g
Distilled water to make ........................................ 1.0 l

Gerald, you have it essentially correct except for one thing.

The rem jet carbon, if left in place throughout the process can begin to accumulate in the developer and get depositied on the emulssion side of the film. Then, during drydown it becomes trapped in the gelatin and leaves permanent black 'dots' in the transparency.

You can do it as you describe but you must be super careful about 'dislodging' the carbon particles. Our method was to wet a sponge in water and then squeeze nearly dry and wipe the film front and back after the rem-jet removal step first in the process. Then, a thorough rinse, and then the process. Otherwise a fair risk of 'black dot'. Our supervisors didn't like that as it messed up the granularity experiments by introducing 'grain'.

Of course, if you are a pirate and get one of those black dots on a page from the Bible, then things take on an entirely new meaning. Heh. I think a few guys with a bad 'black dot' problem in their processes may have moved their supervisors to send them a page from the Bible with a black dot.

Just kidding.

PE