Wolfgang Moersch Photochemie
Am Heideberg 48
50354 Hürth

Tel.: +49-2233-943137
Fax.: +49-2233-943138


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Lesson 1: Basics
Kallitype is a silver-iron process. The light-sensitive substance is, like in a Platinotype, ferric oxalate.

The Kallitype being far more economical then Platinotype is not much different when both are compared. Maximum density (blackening) and gradation curves are similar and the picture tone is a cold, reddish-brown. Toning with noble metals like gold, platinum or palladium is possible. Especially with a gold toner the maximum density is raised. While toning with selenium even after overexposed printing, all densities decrease, the print looks plain and poor in contrast. With carbon toning, the density on shades stays constant, the tone becomes dark brown up to reddish-brown.

Safety advice

Ferric oxalate is poisonous!
Silver nitrate is caustic!
Contact of skin with both substances must be avoided!

The developing substance sodium citrate itself is non poisonous but becomes one during the use through dissolving of oxalate. Therefore handle prints only with tongs.

The emulsion

Silver nitrate at 10% and ferric oxalate at 20% are mixed in equal amounts and applied with a brush or cane on a suitable paper under week, artificial light. After application the paper should left to dry for a few minutes. Once the emulsion looks matte the print can be dried at moderate temperature (30-40°C) with a hairdryer or in a drying cabinet.

On stronger limed papers, Tween can be added into the sensitized solution to provide an even, smooth application. Determining the right amount needs testing but usually one drop of (20%) Tween 20TM on 30-50 drops of emulsion is sufficient. The use of a wetting agent with my preferred paper “Arches Platin” is not necessary. Silver sediments inside beakers and graduates can be cleaned with fixing bath, but
avoiding this from the beginning is the better choice. All beakers and brushes should be cleaned thoroughly right after use with plenty of water. Brushes should be squeezed inside paper towels and gloves be used for protecting the skin from chemicals

The printing negative

Original negatives being developed with staining developers are suitable for use because the stain acts as additional density during exposure with UV lightning. All other negatives have to be copied over to a contrast range of 1.4 to 1.8 logD. As a Kallitype is nothing but a contact printing process, negatives have to be prepared respectively to the size of the desired final print. During the analoguechemical processing a diapositive is obtained from the original negative which is then enlarged onto a film with the required contrast range. Digitally prepared negatives are suitable if the printing foil and ink produce the required amount of high density.


Exposure is made under daylight or for better reproduction reasons with UV lightning. Face tanners, also in larger sizes are sufficient. Exposure times take between two and twenty minutes depending on the distance to the paper and density of negatives.

The use of a contact printing frame allows the control of ongoing exposure. The essential exposure is done when shades change to a delicate red tone. Middle tones should not be visible yet!


As developer I suggest a 20% solution of sodium citrate. There are many other substances cited in photographic literature, all of them work but some are satisfying others not. One problem for users of this technique often seems the bleaching of copies before fixing and thus completing the process. It is therefore necessary to follow the below described workflow.

The print has to be dipped quickly into the developer, with the emulsion side facing up.

It is very important that the whole print is immediately covered with developer, otherwise streaks might be the result. The image appears immediately in a very dark and foggy manner. The print should be kept inside the dish for four minutes or longer, being turned around so that emulsion faces down and be moved in order to wash the dissolved substances easily away. At the end of development the print will appear brighter and richer in contrast as in the beginning.

Clearing bath

After a half minute wash with water the print comes for four minutes into a 3% citric acid bath and finally be washed for 30-60 seconds. If the durance of four minutes is exceeded or the print is washed longer then mentioned it will bleach out.

This example shows how the print has to look before toning or fixing: Too bright with yellow or orange coloured highlights and reddish shades.


Tonings with gold, platinum or palladium or even combinations of these have to be done before fixation!

Tonings are made for following reasons:
- Increasing the durability – Gold and platinum are more stable then silver.
- Increasing the range of contrast – Shades gain density.
- Change of picture tone – e.g Platinum = neutral, or Gold = magenta up to blue.

A slight loss in density through bleaching inside the fixing bath is often given as a result for toning with noble metals. In my opinion, rather the use of unsuitable fixing baths are the reason.

Fixing bath

Within photographic literature, mostly weak baths of sodium thiosulphate are suggested at a quite short duration of aprox. 15 seconds. During fixing only the silver salts which are not involved in “building up” the picture shall be dissolved. At the same time metallic silver should not be attacked immensely by the thiosulphate in order not to be dissolved with the surplus of silver salts. But exactly this seems to happen with some fixing baths if the untoned print gets fixed. If this bleaching would be natural for this process, a more stabilized picture before fixing should be the result through exchange of metals. This should not be seen as an absolution despite such repeated descriptions in some publications.

Fast fixing baths based on ammonium thiosulphate should then be theoretically left out right from the beginning for this particular application. According to my experiences though, I would estimate an alkali ammonium thiosulphate bath as the best choice for the Kallitypie process. I use my ATS-Fixer by a dilution of 1+20 and can not observe a bleaching even after 3-4 minutes of fixing. On the contrary, as soon as the print is brought into the fixing bath a powerful raise of density is the result.

Washing aids

A wash aid (after using an alkali fixing bath) is not absolutely necessary but it reduces the washing time of extra heavy papers like Arches Platin to 10 minutes. A 1% solution of Sodium sulphite, made ready just before use, is quite sufficient for this purpose. The stock solution of my ready to use washing aid can be used for the same result at an dilution of 1+40.


Prints dry smoothly when laid upon drying trays at room temperature. By faster drying inside drying cabins etc. all papers, thinner brands more than heavy weighted, would bend and should therefore be smoothed out at low temperature (50-60°C) inside seal press.

This example shows an untoned Kallitype after fixing bath and drying. The density compared to the wet (not fixed) print had an enormous rise; the prior, garish yellow tone has turned into a warm, pleasant reddish-brown. Finally, a toning is only required if another picture tone is desired or if the print shall be preserved for a few more decades.

Here a print toned with gold toner before fixing for comparison. Even tough exposuring was 10 % shorter the degree of blackening is higher. The definition of highlights is lower but the all around expression is richer in contrast.