Rosie Horn lets her images develop slowly on the actual plant which is how she works with the photosynthesis photographic process.
Overview of the photosynthesis process
Make a positive (not a negative)
- Even out tonal range
- Print on transparency
Pick a leaf
- Vegetable leaves such as Spinach and Pak Choy
- Leaves from undergrowth plants such as Lily, Nasturtium
- Leaves from trees with soft broad leaves
Sandwich together in a contact printing frame
- Make sure the leaf has maximum contact with the positive
Put in the Sun
- Length of time could be half a day to 1 week
Materials for printing photographs with photsynthesis
- Inkjet printer
- Inkjet transparency
- Contact printing frame
Image above right: An example of an image that didn’t get quite enough sun. Good detail but lacking in contrast that would have come from more time in the sun. A bit unevenly exposed from trying to cram to many printing frames into a space to small.
Making prints on leaves is a hit and miss affair. There are a few factors outside of your control that will affect the final outcome, such as the amount of sunshine, the type of leaf and its reaction to the available sun.
The key area to focus on is creating a good positive, this will make the world of difference to your success rate.
After taking photos (I use digital) you then need to process them in Photoshop to convert them to black and white. You need to aim at creating a positive that is even enough in tonal range to achieve maximum detail yet still with enough contrast to make it dynamic. The tonal range of a leaf is narrower than photographic paper. Using Levels helps to even out the tonal range. Avoiding photos with large areas of strong darks and highlights will help improve your results. By masking a dark or light area you can use the levels to even the tone and create more contrast.
I print the finished positive using an inkjet printer onto transparency. I print two copies to achieve enough density, I sellotape them together and then sellotape another layer of transparency over the exposed ink of the print so that it doesn’t stick to the leaf or the glass becoming ruined, the positives should be kept and looked after, they are not throw away items. You may prefer to use traditional negatives which also work well if you get the exposure right, not too dark as they tend to be to dense and the leaf will struggle to pick up any detail.
I would suggest experimenting with making your positive as what has worked for me in New Zealand may not be appropriate for conditions in Europe or North America or wherever you may be.
I then pick a leaf I want use and put the positive on top of it and sandwich it in my contact printing frame. I make sure the leaf is as flat as possible, making sure the frame is very firmly sandwiched together. If the leaf has a particularly solid stem you can build up the surface behind the leaf with card until you can achieve good contact with the positive.
I put this in the sun and depending on the sunlight I check it during the day or in a couple of days. Contact printing frames have a hinge at the back so you can undo half the frame and pull the leaf away from the positive to see how much it has developed. Each leaf will react differently every time, but you will start to get a feel for when the leaf has reached its optimum.
Once the image is on the leaf, the leaf will be very thin and very delicate, as they dry out completely they can become quite brittle so it is important have a book or folder to store them in, something with quite firm pages. To mount them I used some acid free glue and used a small amount to fix them to some Acid free card / matt board.
These images are unfixed, so if you choose to display them bear this in mind. You can always make more.