Scratches on Film

[Thomas Worth]

I just screened a print I had made at FotoKem, and noticed a huge white scratch that lasted for exactly one take. My first thought, of course, that it was due to something trapped in the camera's gate (since it was for exactly one take) but on second thought, wouldn't that mean the scratch would be black? It seems to me that if it's a white scratch, it's the print that's scratched, not the negative. Is there any other explanation for this other than a scratched print?

[Dominic Case]

A white scratch seen on the print is usually due to a base-side scratch on the negative - which scatters light away from it during the printing process.

 

It could also be a very very light emulson scratch - not enough to remove colour dye, just enough to disturb the supercoat layer, and cause light scatter in the same way.

 

A deeper emulsion scratch in the neg will appear yellow or brown in the print where the top (yellow) dye layer in neg is removed, The scratch would appear blue in the neg itself.

 

However, a pre-developer (ie camera) neg emulsion-side scratch can sometimes fog the yellow dye layer rather than remove it, resulting in a yellow line in the neg - blue in the print.

 

A base scratch in the print would scatter light, appearing black on the screen. An emulsion scratch would probably just remove the top (magenta) dye layer, so you would see a green line. A deeper scratch would appear yellow, and a very deep scratch might appear white if all 3 dye layers were destroyed - but almost certainly you would see green and yellow fringes to the line.

 

The lab would certainly have trouble scratching the print for just one take - though nothing's impossible if we lab people set our minds to it ;) .

[Yusuf Aslanyurek]

Thanks Dominic.