Wednesday, November 21, 2018

True sepia, make it simple

The photo above was a normal B&W photo, a little too dark. So, I wondered what could it turn in sepia. To do so, I used a bleach bath made of copper sulfate and sodium chloride for a few minutes, enough to vanish the image. I washed tho photo to remove vestiges of the bleach and soak it in a solution of Sodium Sulfide. The image reappeared but now in sepia.


100 g Copper Sulfate
100 g Sodium Chloride
1 liter water

Sepia bath:

10 g Sodium Sulfide
1 liter water

Tuesday, November 13, 2018

Salt print

Bridge over Lis, Leiria, Portugal

Salt print is one of the easiest (and earliest) print processes from a transparent negative. But there are a number of slight different recipes and some toning methods.

I did the simplest recipe I could find to produce the A4 picture above:

First I printed the negative on a A4 acetate transparency. Then I prepared the paper using a sheet of A4 Canson paper of 300g/m2. The paper was first floated on a 2% salt solution (20g of salt for 1 liter water) and put the paper to dry. After this, under a red light I painted the paper with a 12% solution of silver nitrate (12g of silver nitrate for 100 mililiter) using a smooth brush and let the paper dry.

Using a photo frame I putted the transparency and paper in contact, with the transparency over the paper when the glass is looking up.

Following this preparation, I exposed the sandwich to bright sun for some minutes, until the sensitized paper looked brown enough.

Finally the paper was taken of the frame and subject to a water shower until the water came clear out.

Then I brought the paper to a tray containing a 10% solution of Sodium Thiosulfate (100g for 1 liter). This step took 20 minutes, The paper was left in water for 1 hour and put to dry.