Type of print?

[bob_moulton7]

Can someone define for me a Silver Chloride Contact Print? I understand the Gelatin Silver and Chlorobromide print designations, but I saw references to this type of print in B/W magazine and cannot figure out what it means.

Thanks, Bob

[wb]

Printed on Azo.

[chad_jarvis1]

A silver chloride print is not necessarily an Azo print. I know

Michael and Paula like to refer to their Azo work as silver chloride;

I guess it adds to some degree of mystery. Anyway, there are several

classical paper types that can defined as silver chloride: salted

paper, albumen and POP. The idea is that the paper is coated with

some sort of salt, usually ammonium or sodium chloride, and is then

sensitized with silver nitrate. In order to make the paper light-

sensitive, an excess of silver ions must exist, but in essence the

paper, when light sensitive, ends up coated with silver chloride and

sodium nitrate.<br><br>

 

While we're on the subject, I'd like someone to explain to me how a

silver chloride paper (read AZO) may not a printing-out paper. All

the above referenced papers are printing-out papers. That's the way

silver chloride works when there is an excess of silver ions. Is AZO

different because there is NO EXCESS of silver? Or is there some

other compound at work here (like silver chlorobromide)?

[dhananjay_n]

Hi Chad,

 

<p>

 

My understanding is that POP (salted prints, Centennial etc) and DOP

(Azo) silver chloride papers are mainly different in the way the image

is formed. POP relies on light alone (and huge amounts of it). DOP

depends upon a developer to locate latent image specks and develop

those to a stronger image. In practical terms, this means DOP can have

much higher speeds than POP processes.

 

<p>

 

The excess silver nitrate is POP is required to increase sensitivity

and to produce a "strong" image (without the excess silver nitrate,

images are grey and quite weak). The leading hypothesis is that light

energy dissociates each unit of silver chloride and the chlorine that

is liberated simply unites with the silver nitrate present to form new

silver chloride. Light breaks down this newly formed silver chloride,

and the cycle begins again, to be repeated over and over. When excess

silver nitrate is available, more image silver will be formed and a

greater maximum density attained. DOP papers (Azo is supposed to be a

chloride paper, not chlorobromide) do not need this excess nitrate

since they rely upon chemical development to strengthen the image.

 

<p>

 

I'm sure you've seen this link - it discusses lots of

interesting qualities about the prinintg out processes, including

discussions of how the colloidal nature in POP produce such

distinctive colors.

 

<p>

 

http://albumen.stanford.edu/library/monographs/reilly/chap1.html

 

<p>

 

Cheers, DJ

[michael_a._smith1]

Azo is a silver chloride paper, NOT chlorobromide. N. Dhananjay

explained it better than I could have.

[brian_ellis3]

Which part of the phrase "silver chloride contact print" don't you

understand, the "silver chloride" part or the "contact print" part?

If it's the silver chloride part, as others have explained, that's a

reference to the type of paper on which the photograph is printed. If

it's the contact print part, the term "contact print" refers to a

print made by placing the negative in direct contact with the paper

and exposing the paper, so that the resulting print is the same size

as the negative, as opposed to placing the negative in an enlarger

and making the print by projecting an enlarged image of the negative

through a lens and onto the paper so that the print is larger than

the negative (if I'm talking down to you here, my apologies).