Showing posts with label ferric chloride. Show all posts
Showing posts with label ferric chloride. Show all posts

Wednesday, March 2, 2011

Poitevin's Direct Positive Process: Part 2

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I've spent another afternoon in the laboratory trying to get a readable print with Poitevin's process. I posted a plea for help on apug but no luck so far. To advance any further than I have with my efforts I'm going to have to suck it up and buy A Treaty on Photography which will hopefully have some more tips. The failed procedures after the break.

Sunday, February 27, 2011

'Poitevin's Direct Positive'




Its a snow day here in maine, and i had the required chemicals around so I just gave the formula found
here a go. The source appears to be similar to this version except at appears to be leaving out the gelatin. After a 30 min exposure and a water development i have something of an image (really just some recognizable dark shapes visible against the staining). My second attempt was with a stoffers step wedge and is found at the start of this post.

Attempt 1: Result Failure
Mix the two ingredients together then brush apply to a gelatin sized printmaking paper (I used bfk white).
1/4 inch cube of artist grade liquid watercolor paint
5ml of sensitizing solution

Sensitizing solution:
5 grams ferric chloride
1.5 citric acid 50 ml water
(remember to add acid to water! I forgot and got an awesome steam puff)

Exposed for 30 minutes with negative and test wedges, then developed in hot running water.

Attempt 2: Result Failure
Make a 5% gelatin solution by adding 1 packet of knox gelatin (about 7 grams) to 100 ml of cold water. Let swell for 15 minutes then add cold water to bring the solution to 150ml water. Bring solution to 140* f and maintain the temperature until all the gelatin is disolved. Add 1/4" cube of pigment to the gelatin and stir until an even mixture is created.
Float/brush apply to paper, then while wet float on the same sensitizing solution found in attempt 1.

Expose with test wedges for 30 minutess and develop in hot running water.