alnovo@inwind.it
Date: 09/03/01-09:01:34 AM Z
On 08/03/01-05:34:40 AM Z Malin Hylen wrote:
>Dear all,
>I have recently had a request from a photographer to add his work to
>http://www.cyanotypes.com. He works in a process called 'Resinotypes' I have
>never heard of this process before, and the only thing a search on the
>internet comes up with is that it is a process used mainly in Italy and
>invented around 1920. Does anyone of you know any more about this process?
No replyes confirms that this process did not spread out of Italy.
These are some notes on it, also if I never tried to apply them. However I personally know a couple of photographers in Italy that produced some "resinotypes". The appearance of the prints is "earthy".
The features of the resinotypic process, invented by Rodolfo Namias, can be found in a book titled "Resinotipia", Progresso Fotografico ed., Milano Italy (3rd edition: 1927).
The principle is similar to gumoil and bromoil: here below are the phases of the whole process.
NOTE: the image obtained with this process is a positive, because the pigment will adhere to the swelled parts of the image, so use a positive instead of a negative in the exposing frame.
1) preparation of the resinotipic powder
Mix 3-4 part of a mineral pigment with 10 part of powdered colophony (also called "rosin", is a vitreous solid resin obtained from the sap of pine trees).
Melt the mixture in a small inox pot, stirring it with a glass rod. Colophony melts at 100-120 °C.
Once chilled and solidified, take the melted mixture off the pot and finely grind it with a mortar. The colour of the resulting powder should be similar to the original powdered pigment.
DO NOT use organic pigments because they will be altered by the heat.
2) preparation of the paper
Prepare a solution with 5% of gelatine and 5% sugar.
Spread about 10-15 ml of this solution over a 20x25 cm paper sheet.
Let it set and dry.
3) sensitizing
Sensitize the paper by means of a 5% solution of potassium dichromate for a negative with a 1.4 density range, preferably by immersion, then dry it.
Higher concentrations (up to 10%) will give lower contrast and higher sensitivity, the contrary with lower concentrations (up to 1%).
Adding 1% of sodium citrate to the dichromate solution gives a better swelling capability and a better conservation of the paper.
4) Exposition and swelling
Like usual, expose to UV lignt till a negative, brownish image is obtained.
Wash many times in cold water for about 2 hours.
At the end, pour in a warm water tray (25-30°C to 45°C, depending on the hardness of the gelatine) for a few seconds (5" to 10").
Wipe the excess of water without rubbing by means of a buckskin.
5) dusting
Spread the resinotipic powder on the swelled paper by means of a mesh, then press the powder to the paper by means of a soft brush. Remove the excess of powder with irregular movements of the brush and striking a side of the sheet, mantained vertical, on the table.
6) finishing
Hang and dry, then melt (totally or partially) the dust by means of an hoven or an hair dryer. The partial fusion gives opaque shadows, while the total fusion gives almost shining shadows.
Regards
Alberto Novo
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