To aid the discussion I have put online some examples of the prints
that have inspired my quest. My hypothesis is that we are looking at
autotypy, but please correct me if I'm wrong. All 'faults' listed can
also occur in a 4-colour printing process, but let's first concentrate
on the B&W prints as demonstrated by the JPG's. I have to thank my
'partner in crime' for the extensive description of the faults. If the
text appears funny at points, it is no doubt due to my whacky
translation skills!

1.<a target=_top href="http://www.xs4all.nl/~hkeijser/Images/OLD_NEW.JPG">http://w
ww.xs4all.nl/~hkeij...ges/OLD_NEW.JPG</a>
Here we see an example of two clichées: on the left a 'modern' version
- from the 70's - aluminum alloy with a 'plastic' coating. On the
right an older cliché made of zinc (Zn in the system of elements),
nailed on a wooden block. One look at the edges will tell you how
thick these etched plates are! These cut out-edges, -something that is
done after the etching process-, are typical for this kind of cliché.
It is these edges that show up darker when reproduced as images. On
the one hand because there is more tension around the edges on the
paper during the printing, casusing the ink that lies deeper in the
cliché to be sucked into the paper too. (You see, here I have jargon
problems, it's really hard to translate, I hope it is understandable).
On the other hand, the inking-rolls leave more ink in the 'spaces
inbetween' due to the heightened pressure around the edges. (Of course
this is marginal, but it is a special characteristic which clearly
distinguishes this kind of work from what is generally known as offset
printing).

2. <a target=_top href="http://www.xs4all.nl/~hkeijser/Images/AUTOTYP1.JPG">http:/
/www.xs4all.nl/~hkeij...es/AUTOTYP1.JPG</a>
On this image a number of errors is immediately visible:
A.<a target=_top href="http://www.xs4all.nl/~hkeijser/Images/TYPE1_A.JPG">http://w
ww.xs4all.nl/~hkeij...ges/TYPE1_A.JPG</a>
a dark spot with a halo. In my view this has happened during the
printing:  a grain of dirt has stuck to the cliché, excudes/oozes ink
and is so thick or large, that the surrounding raster-dots cannot be
"inked in" properly anymore. If you look closely, you can see the
raster dots lying behind this grain shine through. This means that the
dirt/grain has been there for a while and has been squashed nearly
completely into to the cliché plate.
b. <a target=_top href="http://www.xs4all.nl/~hkeijser/Images/TYPE1_B.JPG">http://
www.xs4all.nl/~hkeij...ges/TYPE1_B.JPG</a>
light (rasterized) line, dark lumpy things and white spots.
The light line can have originated in a number of ways. It can even be
the case that it was present on the original photograph! The dark
spots indicate dirt between the raster dots, and the light spot is
caused by ink that sticks to the inking roll and does not allow ink on
this local spot. (where dirt, no ink!).
c.<a target=_top href="http://www.xs4all.nl/~hkeijser/Images/TYPE1_C.JPGG">http://
www.xs4all.nl/~hkeij...ges/TYPE1_C.JPG</a>
the left part at the bottom is lighter than the rest - the ink roll
has been irregularly supplied with ink. There are rough, unshaped
areas on the print, indicating more dirt on the inking roll. Clearly
visible in this image are the darker edges of the print.

3.<a target=_top href="http://www.xs4all.nl/~hkeijser/Images/AUTOTYP2.JPG">
http://www.xs4all.nl/~hkeijser/Images/AUTOTYP2.JPG</a> and detail:
<a target=_top href="http://www.xs4all.nl/~hkeijser/Images/TYPE2_A.JPG">
http://www.xs4all.nl/~hkeijser/Images/TYPE2_A.JPG</a>
This print shows scratches on the cliché itself. The raster dots are
damaged and cannot be 'inked in' anymore. The grey spot is caused by
dirt stuck to the cliché plate itself for a longer period of time. On
this spot the plate cannot transfer ink onto the paper very well. The
ink will simply not adhere to the plate in this spot.

Size of the images in the book are 13x18 cm roughly, sometimes bigger
sometimes smaller. HTH.