Since I also sometimes experienced print through, and had the idea that it had
to do with pressure of the roll in the film back, I decided to repeat Tim's
experiment below. At first I did not see the imprint, but if you look very
carefully one can see the figures and forms imprinted in both the non-exposed
film straight out the wrapper and a roll of film ran through a Zenzabronica SQ
(also non exposed),
The print through is actually lighter than the B+F (which is relative high due
to the home brewn developer I use), so it seems that the black ink used for the
numbers is somehow slightly de-sensitising the film. So it's less responsive to
light, although the density difference is subtle, it can pop up in the final
print.
Then I decided to expose a third roll, deliberately over exposing 1/2-1 stop
from my normal speed (10 ASA) and I took a "busy" subject (an old riveted
steel bridge in the city centre), prints form this test did not show imprint.
I do have to carefully check a few more prints which are currently drying.
Best,
Cor
On 7/7/2015 7:33 PM, Tim Daneliuk wrote:
I developed a couple of rolls of APX 25 Ortho today - One, out of the
box, one, transported through a Hasselblad A12 with no exposure.
Both showed signs of print through. This seems to vindicate Richard
Knoppow's contention that this is an ink/backing paper issue, not a
roller transport or exposure-related problem. So, this would point to
a manufacturing defect that isn't a consequence of use, magazine
pressure, or other after-the-fact artifact.
Interesting.