Historical photographic techniques at the National Technical Museum, Prague

Albumin paper photography

The albumin process arose from the perfecting of the salt paper process whereby egg white was used as a binder of sensitive material for sensitising the paper for exposure. The resulting picture is not embedded directly in the paper fibres, but in the layer of egg white. This makes it possible to achieve a more saturated black and greater brilliance and contrast than in the salt process.

Albumin papers were prepared whereby the selected paper was placed on the surface of egg white with dissolved kitchen salt. The paper was dried and then sensitised by placement on the surface of a solution of silver nitrate (under weak tungsten light). The paper had to be thin; otherwise it curled up on the surface of the solution.

Thin paper with a layer of egg white binder curled up even after copying and drying of the picture. That’s why copies on albumin paper were usually stuck to thicker card. If left unstuck, they eventually rolled up. Some collections have a range of albumins in the form of rolls.

Pictures on albumin paper had a significantly reddish colour. That’s why most of them were toned (before fixing) with auric chloride. According to the specific composition of the toning bath it was possible to achieve various shades – most were toned to a pleasant purple brown colour.

Toning increased the durability of the picture. A basic characteristic of egg white binder – susceptibility to yellowing and cracking of the whole layer could not be influenced in any way. Most original albumin photographs are therefore yellow in the light and the sensitive layer is finely cracked.

An example of untoned photograph from are collections is Fig. 1, and a photograph toned with gold is Fig. 2.

Platinotype

A refined technique based on the sensitivity of ferrous salts to light. The picture is formed by platinum, anchored directly between the paper fibres without binder. Platinotypes have very fine, velvety shades, excellent delineation in the shadows without deep black, which preordained this technique for portraits.

Platinotypes were very popular in the USA until about 1918 and many photographers there used it as an important means for their work. It’s great popularity in the USA today (despite the high process costs) is helped by the fact that it often appears at exhibitions of famous American photographers. Further development of platinotype was prevented by the fast growth in the price of platinum, which gradually became an important strategic raw material of the chemical industry. In the Czech Republic only a few platinoprints are represented in collections. An example from our collection is Fig. 3.

Pigment printing and carbon printing

We wrote about the principle of pigment printing and carbon printing in PA No. 4. Paper for pigment printing was also supplied commercially. In our collections we have original advertising samples of The Autotype Company Ltd. – Fig. 4. We have several colour variations of the portrait of a child by Ing. Paspa – Fig. 5. A photograph on Bühler’s commercially supplied carbon printing paper is Fig. 6.

Bromoil printing and bromoil transfer printing

Every good fresh oil print or bromoil print can be transferred by printing onto different paper of absorbent surface. Ordinary soft plate papers were used as transfer papers. The paper was laid on a just coloured damp bromoil print and the whole picture was then transferred by pressure. Examples from our collection are the portrait and landscape from Ing. Paspa – Fig. 7 and 8. They are bromoil transfer prints.

Presentation of historical photographic techniques for visitors to the National Technical Museum

Already in 1988 portraiture with the technique of ferrotype took place under the leadership of Ing. František Pták of Fotochema. A sensitive gelatine emulsion was spread over a black lacquered plate of 6.5 x 9 cm in the darkroom (manufactured at Fotochema, similar to the sensitive emulsion which Foma still supplies to its shops or to order today). It was photographed by a plate camera for plates set in cassettes. After developing, fixing and washing out the photographs were bleached with mercury chloride. The process was thus similar to that used at the end of the 19th century in photographic ferrotype automats. The most well-known was the BOSCO, installed, for example at the Czech and Slavonic Ethnographic Exhibition of 1895 (P. Scheufler: Historické fotografické techniky).

One of the portraits from the event at the National Technical Museum is Fig. 9. According to the recollections of Ing. F. Pták the most difficult phase of the process was the application of the emulsion on the plate – sometimes ugly stains appeared in the picture.

We used the principle of bleaching the ready picture in 2005 making portraits with the ambrotype technique. We photographed with a Sinar camera, 9 x 12 cm format (Fig. 10 shows a photograph from the event). We used Foma Medix PT flat film (film for medical purposes – photography from monitors, format 8 x10 inch). It has suitable sharpness and it is orthochromatically sensitised, so we can spray it with matte black in advance in the darkroom and cut it into 9 x 12 cm format, so it can be placed in the cassette. When taking the portraits we used 500 W bulbs (exposure about 1/10 s). When developing with a normal positive developer the sensitivity was about 200 ISO.

We should recall that for ferrotype and ambrotype we expose just to achieve a weak picture, so that it can appear as a positive against the black background. After developing, fixing and washing out the pictures were bleached with the mercury chloride. Although the given procedure is not complicated, we do not recommend it for beginners. Mercury chloride, used for bleaching, is highly poisonous and only trained people can work with it. The bath is also necessary to dispose of ecologically. An example of a ready portrait from this event is Fig. 11.

Using a Sinar camera with a classical black “nun” we photographed even at the occasion of the commemorative event of the National Technical Museum to mark the hundredth anniversary of the death of Jules Verne in Spring 2005. It was a reconstruction of portraiture on photographic visiting cards. We photographed with a roll cassette for roll film of 6 x 9 cm format. We contact copied the developed film onto Fomatone MG paper, which we developed with a metol-pyrocatechin developer with just 0.5 g sodium sulphite – a pyrocatechin developer without sulphite produces a significantly brown shade. We cut the acquired contact copy (Fig. 13) and stuck it to prior prepared printed cards. The period photographic visiting cards usually also had a distinctive print on the back (an example from the collection is Fig. 14 ), our visiting card of the time had a print relating to the event for the anniversary of J. Verne (Fig. 15).

Creative workshops in historical photographic techniques at the National Technical Museum

More and more people are interested in learning old photographic techniques, but cannot try everything at home. That’s why they welcome creative workshops where they can try making their own pictures under the guidance of instructors.

The first workshops will be focused on the Van Dyke process, then the salt paper process, cyanotype and other techniques. We chose the Van Dyke process first because it is quite simple, fast and not too costly. With it we can show the basic principles of copying processes, sensitisers, types of paper, copying frames, exposure in daylight or under UV light and processing the exposed picture. We count on the fact that our participants will want to continue themselves at home and in view of the fact that the necessary chemicals are not yet available on the market here, we will provide them with the necessary baths. See more at our museum website www.ntm.cz .

Dear readers, this is the end of our series so we would like to wish you success with your own work. If we gain any more knowledge from this area, we will be glad to share it with you once again.