Lith — algunos reveladores

por Domingo A. Siliceo

Hola de nuevo.

Tal y como anuncié en mi anterior entrada, os voy a poner aquí unas pocas fórmulas para preparar reveladores Lith. No es una lista exhaustiva, pero sí es una lista que puede ayudar a quien busque cómo empezar a preparar revelador tipo Lith para sus primeras copias. Creo que hay unas cuantas buenas soluciones.

Este trabajo de recopilación, como os podréis imaginar al leerlo, no es mío sino de Larry Hamilton quien sin poner ninguna pega me ha permitido copiar el contenido íntegro de su página aquí. Él mismo me ha comentado que dicho contenido permanece inalterable desde 2004.

Y poco más tengo que decir: voy a dejar que sea Larry quien se luzca. Disfrutad y sed muy cuidadosos con la preparación de los químicos.


Lith Developers

On this page are formulae for all of the lith developers I could find. Please note that all chemicals should be mixed in the order given and that proper safety procedures should be followed when mixing the formulae. Goggles, a mask and gloves would be regarded as basic precautions.

Michael Gudzinowicz (bg174@FreeNet.Carleton.CA) rather wisely points out that formaldehyde, which is used in many lith formulae, its polymerized form paraformaldehyde and addition products such as the bisulphites, are carcinogenic and should be treated carefully with very good ventilation – preferably in a fume hood.

He offers the advice that instead of using paraformaldehyde, acetone is used. The monomer molecular weight of paraformaldehyde is 30, and that of acetone is 58.08 with a density of 0.788. He suggests therefore, for each gram of paraformaldehyde, substituting 58/(30 * 0.788) = 2.20 ml of acetone. So for 37.5 grams of paraformaldehyde, you’d use 82.5 ml of acetone. He advocates testing this on scrap film with the addition of more acetone if the lith effect does not occur due to the excess of free sulphite.

I’m not sure what effect this has on lith printing rather than lith developing as I am going to stick with paraformaldehyde with care in its use. I’m offering Mike’s advice here for those who are concerned about the use of known carcinogens.

This page points to the following lith developers:


What Lith Developers do

This information was taken directly from an e-mail from Michael Gudzinowicz. It is the best description I’ve found of what Lith Developers do.

Lith Developers are fairly simple mixtures. Hydroquinone is the developing agent, usually present in a concentration of around 20 grams per litre. 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 anti-oxidant properties are retained. The third component is a base, usually carbonate or mixtures of carbonate, hydroxide or borates. The pH is frequently adjusted to a value around 10.

Although lith developers are often thought of as simply high contrast developers, they have a unique property. In the absence of sulphite, the hydroquinone dianon reduces silver and is oxidised to the semiqinone free radical. The semiquinone is a more powerful developing agent than hydroquinone, and it reduces another silver atom and is converted to quinone. Then quinone reacts with hydroquinone to form two semiquinone molecules. They reduce silver, generating two quinones. They react with hydroquinone forming four semiquinone molecules. The rounds of reactions result in an exponential inrease in semiquinone concentration, doubling each time. The addition of sulphite will stop these reactions, since it reacts with the semiquinone and quinone removing the possibility of reaction with hydroquinone to generate more semiquinone.

The semiquinone is generated in the emulsion and remains there with a very short diffusion path. Development starts with grains which have multiple centres. The semiquinone concentration rises as those grains are reduced, and then neighbouring grains are developed which might have just one centre. As the concentration rises a bit more, development spreads explosively (exponential).

What one sees is that development starts slowly in well exposed areas of the film. If a step tablet were used for the exposure, a faint image appears in the well exposed areas. Eventually the developed area reaches a critical density and semiquinone concentration, and then development takes off, and quickly goes to completion in that step. Then as development proceeds, the next step develops fully.

Essentially one has a two phase development. First the formation of a faint image, then rapid completion in areas receiving the most exposure. 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.

Having read the material from Richard and Michael about lith developers, I then consulted my copy of «Photographic Facts and Formulas» (reference on my Library Page) and discovered, in addition to two formulae, a note that Hydroquinone deteriorates slowly in air and has good keeping qualities in solution but is very sensitive to cold and should not be used at temperatures below 60 degrees F. It is practically inert at 55 degrees F. I then went to «The Focal Encyclopedia of Photography» (desk edition), Focal Press, London, 1969 and discovered a table comparing lith developers. I’ve modified it slightly and reproduce the modification here. It gives a different version of Kodak D-8 which is a bit inexplicable.


Ansco GAF 79


Ansco 79 is a single solution formula which is recommended for its convenience but which has poor keeping qualities. If you are likely to store your chemicals then GAF 79b (a two solution version of this formula) is recommended. If you wish to use a single solution developer, Ansco 81 is recommended as having excellent keeping qualities.

Water (<32 dec C)
Sodium Sulfite (anh)
Paraformaldehyde
Potassium Metabisulphite
Boric Acid crystals
Hydroquinone
Potassium Bromide
Cold water to make
500 ml
30.0 grams
7.5 grams
2.6 grams
7.5 grams
22.5 grams
1.5 grams
1 litre

This formula should be used full strength. The normal development time for Reprolith film is given as 2 – 3 minutes. The normal development time for Reprolith Orthochromatic Film is 1 – 3 minutes at 20 degrees C.

Return to the top of the page


Ansco 81


Ansco 81 is a single solution formula which is recommended for its convenience and excellent keeping qualities.

Water (52 deg C)
Hydroquinone
Sodium Sulphite (anh)
Sodium Carbonate (mono)
Citric Acid
Potassium Bromide
Cold water to make
750 ml
35.0 grams
55.0 grams
80.0 grams
5.5 grams
10.0 grams
1 litre

Don’t dilute for use with film. The normal development time is 3 minutes at 20 degrees C.

Return to the top of the page


GAF 79b Paraformaldehyde Developer

This formula I got from an e-mailed message posted by Richard Knoppow in response to a message on rec-photo.darkroom. Richard indicates that this formula might have originated at AGFA. I’ve found that sometimes this formula is given with Solution B made up to one litre rather than three litres. I’ve both checked with references and tried this one out and am confident with the formula given below. In making it up I had a hard job getting the hydroquinone to go into solution. I’m going to read some more about this. Despite the difficulties with the hydroquinone, I had good results with the formula.

NOTE: The use of Paraformaldehyde in this formula necessitates careful handling and the use of proper protective equipment (gloves, mask and eye protection).

Solution A

Water (approx 52 deg C)
Sodium Sulfite, dessicated
Paraformaldehyde
Potassium Metabisulphite
Cold water
to make

_

750 ml
1.0 grams

30.0 grams

10.5 grams

1 litre

Solution B

Water
Sodium Sulphite (dessicated)
Boric Acid Crystals
Hydroquinone
Potassium Bromide
Water to make

_

750 ml
120.0 grams
30.0 grams
90.0 grams
6.0 grams
3 litres

To Use for Films:

Mix one part Solution A with three parts Solution B.

To Use for Lith Printing:

I’ve tried various dilutions and have discovered that the best effects for lith printing were achieved with the following mix:

  • 300 ml part A
  • 900 ml part B
  • 100 ml of Old Brown
  • 8 litres of water

I had to use a big 16 by 20 tray to cope with this volume of developer. Perhaps because of the volume, I discovered that I was able to get quite a few more prints out of a mix than I’d ever achieved with Kodalith RT. The prints came up faster also which makes it a more productive session. Sometimes waiting for 15 minutes for an image to appear palls a little.

I also found that at lower levels of dilution the tones were more brown than pink on the Renaissance paper I was using.

Return to the top of the page


Kodak D-85

This version of Kodak D-85 isn’t very stable and I’d advocate using the two solution version provided elsewhere on this page.

Water (125 F)
Sodium Sulfite (anh)
Paraformaldehyde
Sodium Bisulphite
Boric Acid Crystals
Hydroquinone
Potassium Bromide
Cold water to make

500 ml
30.0 grams
7.5 grams
2.2 grams
7.5 grams
22.5 grams
1.6 grams
1 litre

To Use with Films:

Use undiluted with a development time of 1.5 to 2.25 min.

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

Return to the top of the page


Kodak D-85 (two solution version)

In the same burst of e-mail messages on rec.photo.darkroom, Michael Gudzinowicz gave a two solution version of Kodak D-85.

Solution A

Water (125 F)
Sodium Sulfite
Boric Acid Crystals
Hydroquinone
Potassium Bromide
Cold water to make

_

500 ml
36.5 grams
9.4 grams
28.0 grams
2.0 grams
1 litre

Solution B

Water (90 F)
Sodium Bisulphite
Sodium
Sulphite
Paraformaldehyde
Water to make

_

500 ml
11.0 grams
1.0 grams
37.5 grams
1 litres

To Use with Films:

Mix 4 parts solution A with 1 part Solution B.

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

Return to the top of the page


Wall’s Normal Hydroquinone Developer

Solution A

Water
Sodium Sulfite,
dessicated
Hydroquinone
Cold water to make

_

500 ml
100.0 grams
20.0 grams
1 litre

Solution B

Water
Potassium Carbonate
Water to make

_

500 ml
120.0 grams
1 litres

To Use with Films:

Mix equal parts solution A and Solution B.

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

Return to the top of the page


Eastman D-9 Hydroquinone – Caustic

Solution A

Water
Sodium Bisulfite
Hydroquinone
Potassium Bromide
Cold water to make

_

500 ml
22.5 grams
22.5 grams
22.5 grams
1 litre

Solution B

Cold Water
Sodium Hydroxide

_

1 Litre
52.5 grams

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.

To Use with Films:

Mix equal parts solution A and Solution B. Wall notes that films should be washed thoroughly after development and before fixing to avoid stains.

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

Return to the top of the page


Kodak D-8 Lith Developer

Richard Knoppow provided also, this formula which dispenses with paraformaldehyde. Richard’s formula is as follows:

Water (90 degress F)
Sodium Sulfite (anh)
Hydroquinone
Let cool before adding
Sodium Hydroxide
Potassium Bromide
Water to make
750 ml
90.0 grams
45.0 grams

37.5 grams
30.0 grams
1 litre

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.

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

Return to the top of the page


Ilford ID-13


I’ve not been able to find out much about this developer other than it is for line and screen negatives.

Solution A

Water
Hydroquinone
Potassium Metabisulphite
Potassium Bromide
Cold water to make

_

750 ml
25.0 grams
25.0 grams
25.0 grams
1 litre

Solution B

Cold Water
Sodium Hydroxide

_

1 Litre
50.0 grams

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.

To Use with Films:

Mix equal parts solution A and Solution B immediately before use. This solution has very poor keeping qualities. With normal exposures development is complete in 2.5 to 3 minutes.

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

Return to the top of the page


Packo Lith Developer

Water (<32 dec C)
Sodium Sulfite (anh)
Sodium Formaldehyde bisulphite
Hydroquinone
Sodium Bromide
Sodium Carbonate (mono)
Ascorbic Acid
Cold water to make
500 ml
3.0 grams
25.0 grams
12.0 grams
2.6 grams
23.0 grams
5 grams
1 litre

This formula should be used full strength. The normal development time for film is given as 2 minutes.

Return to the top of the page


DuPont D-7

Water (<32 dec C)
Sodium Sulfite (anh)
Paraformaldehyde
Sodium Bisulphite
Boric Acid crystals
Hydroquinone
Potassium Bromide
Cold water to make
500 ml
60.0 grams
15.0 grams
5.0 grams
15.0 grams
45.0 grams
3.0 grams
1 litre

This formula should be used diluted 1+1. The normal development time for film is given as 2 minutes.

Return to the top of the page


Welliver & Krizka Lith Developer


Michael Gudzinowicz provided this formula with the comments that stability has always been a problem with lith developers and most only have a working life of 2 hours or so. Ascorbate extends life by a small amount, but interferes with activity. By using metaborate as the base, the open tray life of this developer has been extended to 8 hours.

Water (<32 dec C)
Hydroquinone
Sodium formaldehyde bisulphite
Sodium Carbonate
Sodium metaborate
Potassium Bromide
Cold water to make
500 ml
15.0 grams
50.0 grams
20.0 grams
20.0 grams
1.5 grams
1 litre

I’ve got no information about using this developer

Return to the top of the page


Acetonitrile Antioxidant Developer


Another approach to increasing the storage life of a lith developer has been to use acetonitrile as an antioxidant.

Water (<32 dec C)
Sodium carbonate (mono)
Paraformaldehyde sodium bisulphite
Potassium Bromide
Hydroquinone
Sodium Sulphite
Acetonitrile
Cold water to make
500 ml
50.0 grams
45.0 grams
2.0 grams
18.0 grams
2.0 grams
10.0 grams
1 litre

I’ve no information about dilution but that film should be developed for 2.75 minutes at 20 degrees C.

Return to the top of the page


Gracias por leer.

Anuncios