Very cool Daire
seems you have made a type of paper colour negative , when scanned you have brought out a nice image.
Silver halides are capable of producing several colors when exposed to light without development. The color depends on the size of the silver grains. The images cannot be fixed and so have limited practical value. Google on Lippmann plates such as http://en.wikipedia.org/wiki/Lippmann_plate
Last edited by Gerald C Koch; 01-26-2014 at 11:30 AM. Click to view previous post history.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.
~Antoine de Saint-Exupery
I've been playing with this for the last year or so and I'm convinced it is a worthwhile way to make beautiful contact prints, with colors and a look different from other contact printing methods. The difficult part is keeping those highlights clear while developing enough density, and stopping before the shadow details gets muddy. My best results so far are all from (paper) negatives that have been made for this process. The negatives that work well for salt prints work well for this. There is a delicacy in these prints that is lovely, but with a different look and different colors from salt prints.
Every paper I've tried ( 6 kinds so far ) has a different look and different characteristics. I soak the paper in dilute KN03 for 10 minutes, and then press it tightly while still wet to a paper negative. Then it goes inside a ziplock bag and under a sheet of glass for exposure. If you add lemon juice or vinegar during the soak it will change the color, speed and ultimate density of the printing out. My favorite "recipe" right now is 1/8t KN03 in 2oz of water with 5 eyedroppers of filtered lemon juice. Other combinations work too, and it is a matter of personal taste which color and look you'd like the best.
With the right negative, it is possible to keep delicate pure white highlights and still develop dark enough shadows.
I've had less luck with letting the paper dry before exposure but it is easier to avoid stains and "blurry" areas that happen from uneven pressure on the wet print. In the past few months I've found a combination of paper/soak that I really like and I'm planning to revisit it as a dry contact print. If you try it wet, do wash your negative soon after the exposure... I've ruined a couple by letting them sit for a couple days in the bag still wet. Also you want to run tests first on negatives you don't care about, just to verify that they are not harmed. All my negatives are on RC paper, and so far no problems unless I leave them wet for days ( then the emulsion comes off! )
I wash mine briefly in highly dilute salt water, then fix twice, 5 minutes each, in weak hypo. Then 3 minutes in 1% sodium sulfite and a long wash. The image will almost disappear in the hypo, and there is a huge color shift at that point, but it comes almost all the way back when it dries. It's quite dramatic. Then toning in weak KRST can look really nice, but don't go too far... it starts to get a neutral light grey ( which might look nice in some, and is easy to control and cause splits )
Honestly, I had almost given up on this ( or at least, was about to try brushing on weak AgNO3 or some other approach ) until a friend sent me some 40 year old Kodak polycontrast single weight FB paper. This stuff makes lovely contact prints this way and I'm excited about the process again. The past couple months I've been making paper negatives specifically for this and for salt printing.
My exposure times under a single BLB fluorescent tube are usually around 2 hours. I have not tried the sun again recently, and not since I started making good negatives specifically for this process. I'm hoping that a dry contact print in the sun will work, like it does for salt prints because that will be more convenient.