Reticulation is the distortion of the emulsion layer of a film, caused when it is taken from one bath to another that has a dramatic difference in temperature. If for example you take the film from a warm developer to a cold fixer or from a warm fixer to a freezing wash the film may reticulate. This is because the sudden and dramatic change in temperature forces the emulsion to expand or contract causing grain to cluster together into larger collections.
With today's modern film emulsions it is very difficult to create reticulation, because manufacturers have gone to great lengths to produce better quality emulsions that can withstand sudden changes in temperature. When using a hardening fixer the emulsion is made more resistant to scratching which again will prevent reticulation on the final wash. I found the best film to produce reticulation is the old Adox film Efke. Its emulsion is very soft and cant cope with sudden temperature changes. I developed the film as normal and used Ilford Hypam to fix it, but at the washing stage I increased the temperature from the usual 20 degrees to 40 degrees. My first attempt was ruined when I used film squeegees to help remove excess water, the emulsion was so soft it came away with the water. I was left with a beautiful peace of clear film! I now handle the film with extreme care to avoid catching the surface, which can easily remove chunks of emulsion.
Millstones are a prominent feature around Derbyshire. This clump, near Stanage Edge, provides an interesting foreground for many photographers. I used a green filter to lighten the grass which has darkened the reds in the surrounding heather creating a patterned ground, the reticulation has merged these shades making the print look as though it has been roughly sketched by an artist. I had to touch up the digital scan on one of the millstones because I accidentally caught the negative in processing which removed the emulsion.
This was taken by a reservoir in Derbyshire, in the foreground lies an old wrecked car - the insides had been set on fire - probably an insurance fiddle! I placed the foreground horizon on the first dissection using the rule of thirds.
It's difficult to see the effect of reticulation at this screen magnification so the area within the red square has been enlarged to show just what happens to the film emulsion and grain.
Another viewpoint of the same wrecked car, with a beautiful course pattern created by reticulation.
The amount of reticulation is more apparent on continuous tones so when a subject has been exposed as a silhouette you won't see much of an effect. You still get the dots in the emulsion where due care hasn't been taken in the processing.