B&W 16mm reversal film came out clear! Why?

[Taylor Page]

Hi guys,

I recently processed a test strip of Kodak B&W 16mm Tri-X 7266 and it keeps coming out clear after I take it out for re exposure! Clear, as in, no indicating marks what so ever. Completely blank. I'm using D19 + Potassium Thiocynate for the 1st developer and permanganate bleach for the bleach bath. Am I over or under developing? The tank is light tight and nothing is wrong with the camera or exposed roll.

 

[railwayman3]

Hi guys,

I recently processed a test strip of Kodak B&W 16mm Tri-X 7266 and it keeps coming out clear after I take it out for re exposure! Clear, as in, no indicating marks what so ever. Completely blank. I'm using D19 + Potassium Thiocynate for the 1st developer and permanganate bleach for the bleach bath. Am I over or under developing? The tank is light tight and nothing is wrong with the camera or exposed roll.

Many years ago (at the school Camera Club !) we tried reversal processing B&W film. One of my friends left the film in the permanganate bleach for longer than the official time, with the result that the bleach bath completely removed the emulsion. Were there any traces of stripped or dissolved emulsion when you took the film out for re-exposure ?

 

[pdeeh]

It will help others diagnose this if you give the formulas and times you are using, rather than just a broad description, the composition of the 1st dev in particular.
D19 is uncommon - I don't think it can be purchased can it? - so presumably you are making it yourself. Any possible problems therein?

I'd also want to know that you're sure the film you're developing was exposed properly.

 

[guangong]

As pdeeh commented, you need to provide more details about processing. Generally speaking, permanganate is not the preferred bleach.
D19 hasn’t been available for the last few years, but easy to make. I even made it when available packaged because sometimes a gallon was more than needed.
While the second developer time has a wide latitude, other times should be as accurate as possible. Temperatures also.
Also, are you using fogging bath or reexposure?