Black and white reversal Re Exposure question

[Stephen Frizza]

Ok as I mentioned earlier Ive been processing black and white reversal with good results, But I have a question regarding the re exposure step I am curious if you don't re expose it to a complete spectrum can you alter the tonality in the final slide? say if the light was more blue or more red on the re exposure can you cause the final slide to have a lighter or darker sky? etc?

 

[Ian Grant]

You're not supposed to grossly overexpose the film in the re-exposure stage. The film will have lost most if not all of it's panchromatic sensitivity in the first developer, but over exposure to daylight & blue light can cause problems with the remaining image partially reversing again. This is the principle of Direct reversal films & papers.

Some older processes gave a measured re-exposure to light and didn't develop to completion in the 2nd developer.

In conventional B&W printing an unsafe Red/Orange safe-light can cause image bleaching with some VC papers. The safe-light may pass all normal fogging tests but the results are you cant achieve the highest grades., this is the reason for the Brown/amber VC safe-light filters.

This is an effect with a B&W emulsion where the exposure to 2 different wave-lengths produces the opposite of what you'd expect.

Ian