Adox/Efke coated using "dip and dunk"??

[PHOTOTONE]

On the Adox website, English pages, it states that the traditional Adox films and papers are coated on the "last coating line" using "dip and dunk" coating as opposed to the horizontal coating methods used for more modern materials.

I associate "dip and dunk" with the large tank method of processing film, which I indeed use for E-6 and C-41 processing myself, where the film is lowered into the chemistry and is raised up and down within the chemistry for agitation. What I cannot seem to grasp is how this term: "Dip and Dunk" could relate to coating an emulsion, since "dunking" would get the emulsion on both sides of the paper or film stock, rather than on just one side. Can anyone "in the know" explain?

 

[Photo Engineer]

There are two possible dip and dunk coaters that were used about the same time. In one, the paper or film was passed face down into a trough of developer while being held tightly against a drum. The pressure against the drum prevented wetting of the back. As the coated support came out of the tray, it travelled upwards and past a knife (a doctor blade just as I use) that scraped off excess emulsion and let it run back into the trough. The coating ran the full width of the support.

The other method used the same setup but with an intermediate offset drum that was about 1/2" less wide than the support. The drum picked the emulsion up from the trough and then gently 'kissed' the surface of the support as it passed between the wet drum and a dry drum on the back. After this, there was a knife again to scrape off the excess emulsion.

Later machines used an air knife instead of a metal knife, but this was subject to nonuniformity.

Both methods were abandoned in the 40s or thereabouts by Kodak in favor of an extrusion method, and later were abandoned for the slide and then curtain coating methods.

BTW, this is also in a rather extensive post on coating methods.

PE