Mass market print - what type of repro?

I'm guessing this print dates 1920s-ish, give or take a decade. There's no artist siggy and, more surprisingly, no printers mark. There's a matrix pattern in the print, but more cellular than dot. What type of print would this be? Measures approximately 18" by 12" (excluding the rather handsome frame).

 

Possibly letterpress halftone?

http://www.graphicsatlas.org/identification/?process_id=102#overview

Fig

 

I guess that must be what it is, though I'm not 100% convinced. The description from that site does say, "Four color prints with an AM screen typically have a rosette pattern which is formed because each color separation is given a screen made at a different angle, each of which is specifically calculated to avoid moiré patterns."

I've had a lot of prints that it hasn't bothered me to call halftone but, looking at them now, I see a lot of variation in the dot patterns. IDs are just not as straight forward as might be hoped.

Thanks for looking.

 

I've seen similar dot patterns in other early photo-offset prints. I don't know the history, but it seems like the techniques used evolved over time.

 

Here's an enlarged section of the dot matrix:


Here's a comparison of offset lithography and digital press, good because it clearly depicts a rosette dot pattern:
http://www.dp3project.org/resources/newsletter-archive/v7/idtip-offset-litho-or-digital-press

The tighter magnifications in the link show dots of individual color, which I don't see in my print. It is possible that that is just because I don't have the equipment to get that tight a view. (The photo above is just an enlargement of the previous photo, which is as close as my camera can handle.)

Given that letterpress halftone and offset lithography can both produce rosette dot patterns, the question becomes: which technique was more likely to be used in production of this print? Beats me, but it may be a question of volume. Both techniques were available when this print was made, and I don't even need the date of the print to say that.

 

For some reason the Graphics Atlas doesn't have their page posted about offset lithography, and they also don't show an example of rosettes in the letterpress halftone process. I know they recently were tinkering with formatting. Maybe it disappeared at that point?

The past you linked to is great.