From: dan.c.quinn on
RE:On Oct 21, 11:35 am, piterengel <pslavi...(a)interfree.it> wrote:
>
> Hi, becaise it no more possible to find lith film I need to try with a
> qute common film to obtain very high contrasted pictures. I have Efke
> KB 25 and Rollei PAN 25 at home. Can anybody suggest a developer
> to have extremely contrasted subjects? > Thanks all - P.
>

A variety of lith films are available here in the USA. Lith films
are slow orthochromatic films which are processed in well lighted
darkrooms; the same level of lighting used to process Graded Paper.
Any film I'd think would lith process. Panchromatic film processing
would be done in complete darkness. So, slow ortho films are used.
As for developer a very low sulfite carbonate plus hydroquinone
mix will likely work well; does for paper. Dan


From: Nicholas O. Lindan on
As regards not using (para)formaldehyde for lithographic
film development I have tacked to the corkboard in the
darkroom:

> Kodak D-8
> Richard Knoppow provided also, this formula which dispenses
> with paraformaldehyde. Richard's formula is as follows:
>
> Water (90 degrees F) 750 ml 7 oz
> Sodium Sulfite (anh) 90 gm 3 tsp
> Hydroquinone 45 gm 3 tsp
>
> Let cool before adding
>
> Sodium Hydroxide 38 gm 1.5 tsp
> Potassium Bromide 30 gm 2 oz 10% soln
> Water to make 1 litre 8 oz
>
> Richard notes that the solution should be stirred thoroughly
> before use. He also suggests that a less alkaline version
> which will give nearly as much contrast can be obtained
> by reducing the amount of Hydroxide to 28 grams per liter.
> He also wisely notes that one should be very careful mixing
> the hydroxide as it produces a lot of heat going into solution
> and can cause boiling and splattering. Hydroxide should only
> be added to COLD solutions.
>
> To Use with Films:
> Mix 2 parts stock solution and 1 part water.

I added the 8 oz make-up - about right for a few sheets of
4x5 in a tray.

The paper on the corkboard doesn't list its provenance,
but it appears here:

http://members.iinet.net.au/~forbes/lithdev.html

with the additional comment:

> To Use for Lith Printing:
> I'm going to experiment with this developer and
> post my preferred dilutions for lith printing.
> Until I do, I suggest that you consult Tim Rudman's
> book for ideas on diluting it for use in printing.

I use this stuff with lith film and it works well, not as
dramatic and dense as Kodalith A/B but certainly workable.

The _original_ formula was obviously:

Water (90 degrees F) 24 oz
Sodium Sulfite (anh) 3 oz avdp
Hydroquinone 1.5 oz avdp
Sodium Hydroxide 1 oz avdp
Potassium Bromide 1 oz avdp
Water to make 1 quart

Formulae with 85.1 gm of this and 38.35 gm of that give the
impression that titrations of great precision were used
in determining the optimum amounts. The amounts only
look funny because they got converted to metric, rounded
(or not) and then tweaked with 'and extra 10 ml or so'
yielding numbers like 38.35 ml.

The quantities used when the formula was developed are
obviously a jigger or this, a splash of that and a
teaspoon of the other. When making it up there is
no need to be any more precise.

==
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121


From: Nicholas O. Lindan on
"Nicholas O. Lindan" <see(a)sig.com> wrote

>> Water (90 degrees F) 750 ml 7 oz

Oops, that should be 5 oz

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.darkroomautomation.com/index.htm
n o lindan at ix dot netcom dot com


From: Richard Knoppow on

<dan.c.quinn(a)att.net> wrote in message
news:1193174524.449215.97660(a)i38g2000prf.googlegroups.com...
> RE:On Oct 21, 11:35 am, piterengel
> <pslavi...(a)interfree.it> wrote:
>>
>> Hi, becaise it no more possible to find lith film I need
>> to try with a
>> qute common film to obtain very high contrasted pictures.
>> I have Efke
>> KB 25 and Rollei PAN 25 at home. Can anybody suggest a
>> developer
>> to have extremely contrasted subjects? > Thanks all - P.
>>
>
> A variety of lith films are available here in the USA.
> Lith films
> are slow orthochromatic films which are processed in well
> lighted
> darkrooms; the same level of lighting used to process
> Graded Paper.
> Any film I'd think would lith process. Panchromatic film
> processing
> would be done in complete darkness. So, slow ortho films
> are used.
> As for developer a very low sulfite carbonate plus
> hydroquinone
> mix will likely work well; does for paper. Dan
>
Lithographic films were made in all spectral
sensitivies, pan films were used for making half-tone plates
for three or four color letterpress reproduction. The main
property of lith films which differentiates them for
pictorial films is their contrast. The contrast of a film
depends on certain features of its emulsion, mostly the
range of sensitivities of the silver halide particals which
make it up. Pictorial film has wide range of halide
sensitivity, lith film a very narrow range. So, for a lith
film the difference between an exposure which results in
full development and one which does not expose a partical
enough to develop it is very small. The result is that the
image is essentially either full density or none.
Lith film was used originall for photo-mechanical
reproduction of line or half-tone work, the latter using a
screen. The original half-tone process used a variation of
the wet-plate Collodion process because the senstive
coating (not an emulsion) could be very high contrast and
was very thin which maintained the sharpness of the dots or
lines. Later various types of lithographic dry plates were
used including some with the half-tone screen built in.
There were also a variety of "commercial" films, often
blue sensitive but also ortho or panchromatic, meant for
very high contrast but lower than the lith films. All of
this stuff has been replaced by digital methods for
photo-mechanical purposes but lith film remains because it
is used in a number of alternative photographic processes
and for special effects such as masking.
The lith developers using Paraformaldehide must be low
sulfite because sulfite interfers with the infectious
development property. Infectious development is the
accelerating development of silver halide particals near a
developing one. This produces a sort of chain reaction which
results in very high density and very high contrast.


--
---
Richard Knoppow
Los Angeles, CA, USA
dickburk(a)ix.netcom.com


From: dan.c.quinn on
> "Richard Knoppow" wrote:
>
> ... but lith film remains because it is used
> in a number of alternative photographic processes
> and for special effects such as masking.
> Richard Knoppow Los Angeles, CA, USA
>

Check your local printing supply outlets or visit via the WWW
Valley Litho, a Mid West mail order supplier of a vast selection
of press room supplies including a large selection of lith - half
tone process films and developers.
Should add, also a somewhat unique assortment of film,
paper, and darkroom supplies. Dan


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