Obra Cultural Fotografiamartell, Fotografía Química, Creativa y Artistica


PYROCATECHIN "TANNING IMAGE"

Introduction:

The conclusions Shown in this essay result From several months of personal research, using my Own formula. This tanned image isn´t suitable for commercial use and neither are the high-tanned gelatine formulae published, since they requiere the addition of enough amount of sulphite in order to avoid de high-tanned effect wich would favour their preservation and commercialization. The reader can experiment and obtain these effects, Knowing that they are absotutely individual.

>Catechol itself can develope high-contrast negatives and in spite of the gelatine being permanently tanned, the factors time of developement and amount of exposure will enable you to obtain, if the Developer agent is mixed correctly, a negative exhibiting a yellow tone resulting from the exhaustion of Pyrocatechin during processing (Rev-h) wich will reduce the contrast of the bright lights and favour the emergence of softer shades in negatives close to extreme contrast. On the other hand the characteristic yellow tone of the tanning process may be avoided by varyng some factors as aforementioned, leaving an even more contrasting negative almost Lith that Pyrocatechin itself cannot offer. This shall be further discussed in the next study called Pyrocatechin II (High contrat negative).

Another Subject to address in future essays will be the effect of Pyrocatechin in paper developer agent, the achieving of intense shades as well as high-contrast copies in neutral or different colourings.

It is important to consider the materials (paper and film) that better suit this type of work.

All material used in this experiment were purchased through Foto-r3 because of their known quality standards and their interest in black and white photography.

The digital interpretation of images is neutral (for the correct viewing of colour the monitor should be set to a minimum of 6500ºK) respecting as much as posible the human sight, without digital processing or editing, except for the necessary adjustements to 300x500 ppp the approximate size of the original copies in low speed barited chlorobromide paper 18x24, wich were made exclusively for this study. The resulting scanned images required virtually no adjustements to shade and contrast.

The idea for essay as many other that appear in fotografiamartell is the recovery of the memory, providing alternative tools to those experts who seek to compose distinct and creative black and white images, or perhaps it is simply an attempt to spread information relative to this art and to the research conducted in black and white or analogical photography labs.

The underlined message is that monochromatic photography be it traditional, analogical or simply black and white is still meaningful, despite the tendency to prefer more elaborate material particularly in Spain. This is due in my opinion to the excesive BBC culture (Bodas, Bautizos y Comuniones), insufficient information on artistic imaginery, to the constant pursuit of profit ignoring quality standards and to the cultural lacks in information and support by the concerned institutions throughout the years, etc.

Catechol used as a developer agent not only provides images with singular characteristics but also it is easy to mix in order to obtain various levels of tanned effect from the consistency of the gelatine. Furthemore it may offer a mordant surface to add colourings and a range of posibilities that make it one of its kind.

Pyrocatechin proof with low Sodium Sulphite content.

These image are meant to be sold and/or exhibited. Any sort of copy is absolutely forbidden.

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Image scanned directly from paper Forte Polywamtone 15 Plus FB, (low speed chlorobromide emulsion). Size 18x24.

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CHS 50 ART film from ADOX, now called EFKE KB 50, EFKE KB25 y la KB100 may be also used. Size 18x24.

I have recently experimented with Rollei Pan 25 and got very good results bacause all these films are excelent quality and rather inexpensive as well.

In the image Above of the negative developed with Pyrocatechin the higher density areas show a hard gelatine that even after a full bleached process preserves the image, since the tanned gelatine would allow its recovey and developement though the emulsion is silver halide free.

Some precautionary mesures should be taken when handling Pyrocatechin or Catechol (names more commonly used in photography) namely to avoid breathing the powder and all contact with skin and eyes (wash off with water). If these indications are observed there shouldnt occur any hazards. This Kind of products warrant proper recycling because of their contamination nature.

The quantity of sodium sulphite is a basic factor to be considered at the time of mixing the formula. Regardless of How much you add, as can be seen in the pictures below the gelatine will always exhibit a grey colour and the silver resultant will be brown. The variation in quantity of sodium sulphite produces, if little is added, an intense shade of grey but larger amounts render it paler grey.

Pyrocatechin proof developed with medium-high sodium sulphite content.

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In the negative (enhaced x2) the tanned area can already be intuited, therefore more sodium sulphite could be added.

 

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The scanning of this image directly from the negatives justifies the presence of brown silver wich is the characteristic shade of the silver halide filaments, resulting from the reduction in Pyrocatechin.

In a more elaborate way it could be said that the products generated by Catechol processing are eliminated or neutralized to some extent, altering the developement since they act as reaction catalysers. Thus, processing time will vary according to the quantity of sodium sulphite added to the formula, as will all other factors.

Pyrocatechin solutions in weaker concentrations are only usable for 2 hours. Beyond this period of time the level of exhaustion thorugh air oxidation will prevent the results from being homogeneus, constan and therefore repeatable.

Tanning the image with Catechol causes the negative to slow a thickening of the gelatine in its greater density areas unlike the smaller density or unprocessed areas. In addition, these thicker areas exhibit a grey-shaded gelatine that when exposed to the enlarger´s light functions as a filter, accentuating the contrast in the print considerably and causing the negative to act as if it were denser. These effects will be more apparent depending on the choice of paper (bromide or chlorobromide) and the usage of difusion or condenser enlarger.

It should be considered that this product isnt marketable, it isnt preservable due to oxidation. Another factor that may produce influence the level of tanning is the density of the gelatine coat of approximately 75 microns (often larger quantities have produced more visible tanning) but ultimately it will alkways depend firstly on the formulation, then on the exposure and finally on the agitation rhythm.