Hi:

Here in my country it is almost impossible to get a developer for the lith print (infectous) process, or when available very expensive and/or only large quantities. I was looking for a formula for such a lith print developer, in order to mix it myself. Does somebody have such a formula at hand ?

-- Marc Leest (classicphoto@leest.net), February 06, 2002

Answers

Lith Developers are fairly simple mixtures. Hydroquinone is the developing agent, usually. The free sulphite level must be very low - less than 2 grams per litre. Since the developer will oxidise quickly, sulphite in the form of an addition product with formaldehyde is frequently used, or formaldehyde, paraformaldehyde or acetone are added to tie up free sulphite. The third component is a base, usually hydroxide. The pH is frequently adjusted to a value around 10.

I suggest Rudman's book for an explanation of how a lith developer builds an explosive, chain reaction. Essentially one has a two phase development. First the formation of a faint image, then rapid completion in areas receiving the most exposure due to the explsoive formation of semiquinones. This results in a film with very little density in areas with little exposure, and an extremely dense image in areas with a bit more exposure. As expected, the contrast increases with development to a miximum after 1 to 3 minutes, and then decreases as the low value faint images are further developed. Unlike developers with moderate sulphite concentrations, development is restricted to the grain and filaments are not formed. If free sulphite is added (20gm/l), filaments are formed and neighbouring grains are rapidly developed. There is no lag phase and significant semiquinone concentrations are not generated. The developer then acts like a typical MQ or PQ high contrast developer.

The following are a couple of illustrative lith developer formulae.

Eastman D-9 Hydroquinone - Caustic

Solution A Water 500ml Sodium Bisulfite 22.5 gms Hydroquinone 22.5 gms Potassium Bromide 22.5 gms Cold water to make 1 litre Solution B Cold Water 1 litre Sodium Hydroxide 52.5 gms

Note: Cold water should always be used when dissolving sodium hydroxide because considerable heat is evolved and if hot water is used the solution will boil violently and may spatter and cause serious burns on the hands or face.

Kodak D-8 Lith Developer

Water (90 degress F) 750 ml Sodium Sulfite (anh)90 gms Hydroquinone 45 gms Let cool before adding Sodium Hydroxide 37.5 gms Potassium Bromide 30 gms Water to make 1 litre

Hope this helps. Cheers, DJ.

-- N Dhananjay (dhananjay-nayakankuppam@uiowa.edu), February 06, 2002.

Hi Marc,

if I remember correctly you are from Belgium, arenīt you?

Is it too expensive to have the chemicals sent from Germany? I mean, now that we all have this one currency....

You could try www.mahn.net or https://ssl.kundenserver.de/shop.fotolaborgeraete.de/lumiere- uk/shop/index.htm for the excellent Moersch Photochemie.

Quantities in both cases are as usual.

HTH,

Sandra

-- Sandra (SSchaenzer@web.de), February 18, 2002.

Marc,

I ordered some MACO lith developper from FotoImpex (Berlin, www.fotoimpex.de) and am very happy with it. Available in very small to large quantities. Easy and fast delivery...

BTW, I use their Classic PWT (Forte PWT clone?) for a few months now for "normal" B&W and Lith B&W prints. Very satisfied.

Regards, Dirk (Gent, Belgium)

-- Dirk De la Marche (dirk.de_la_marche@alcatel.be), February 19, 2002.