Digital BW, The Print

Actually the traditional sepia started as a product of cuttlefish 
pigment. Quite Brown in color. GOT SQUID?  

Jeff




> Paul Roark wrote:
> 
> >
> > The sepia tone I ended up with was set after studying my own 
samples 
> > of old
> > photos and a number of books.  I thought the most authoritative 
was a 
> > French
> > government sponsored History of Photography.  I figured they had 
the  
> > money
> > to make the best reproductions.  One thing I think I saw was that 
the very
> > common albumen prints seem to become more yellow with age or 
light.
> >
> 
> This may be very basic stuff for many here, but with the size of 
the 
> group, I thought it might be good to take a moment and cover this 
ground..
> 
> "Sepia:"
> 
> What is it really?
> 
> To my knowledge there are four different, but. at times. quite 
visually 
> similar, processes that result in "sepia" images.
> 
> 1)    Fading and sulfidization of silver gelatine prints - in this 
> process exhibited by many older prints, both airborne sulfur ions 
and 
> sulfides left in the print by improper fixing, clearing, and 
washing 
> will combine with the image silver  - in such a case, the sulfide 
ion 
> joins the silver molecule and a more stable silver sulfide compound 
is 
> produced
> 
> 2)    Fading and yellowing of albumen prints -  residual sulfates 
and 
> thiosulfhates from developing that remain in the paper cause 
yellowing 
> of the paper itself and as in #1 join with image silver to form 
silver 
> sulfides
> 
> 3)    Van Dyke Brown/BrownPrint  -   A process in which an image is 
> initially exposed onto silver salt sensitized paper and then 
developed 
> in a thiosulfate solution -- the sulfur joins with silver of 
exposed 
> silver salts in the actual developing of the print - this forms a 
> brownish image of Silver Sulfides
> 
> 4)    Sepia Toning - After exposure, developing, and fixing of a 
> gelatine silver print, a sulfide or polysulfide solution is used to 
join 
> sulfur to free silver molecules in the image - the longer the 
toning, 
> the more sulfide molecules created in the print, and the more brown 
the 
> final image
> 
> The variety of  tonalities of "sepia" prints may, in part, be 
traced to 
> the fact that "sepia" is really an inexact term describing the end 
> result of these different processes..
> 
>  In fact, the tonalities are even wider than it seems.. As in #4 
above, 
> the final results in hue (more or less reddish or olive-like) 
depend 
> upon not just the actual toning, but, will appear differently in 
> chloride or bromide papers AND depending upon what the actual 
developer 
> was  (warm-tone or cold-tone developers  mated with sepia and 
differing 
> paper types will give differing hues)
> 
> We also generally tend to think of selenium toned prints as 
purplish or 
> exhibiting "colder" tonalities..  In fact that is only true with 
Bromide 
> papers -- chloride papers when toned with selenium can go to a 
reddish 
> brown and be mistaken for sepia toned images.  Moreover, with some 
> chloride papers and a warm-tone developer (PQ or Agfa) followed by 
> Selenium toning, I have toned silver gelatine prints to a near 
> orange-red image.
> 
> Sepia toning, selenium toning, gold toning, etc., were developed 
out of 
> a need to make silver prints more archival, by preventing image 
silver 
> from oxidizing.
> 
> Given the preceding it should be clear why sepia tonalities are 
really a 
> personal taste, like the choice of cold or warm base papers, etc.  
The 
> causes of traditional  "sepia" images are varied, and 
concomitantly, so 
> are the tonal and hue ranges that would be covered by the rubric of 
> "Sepia"..
> 
> 
> 
> 
> [Keith]
>  
>  
> 
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