Photographic images are developed on natural leaves through the action of photosynthesis.
The photo-bleaching Chlorophyll Processes works due to the pigments in leaves (Chlorophyll-a) and flowers and vegetables (Flavonoids) respectively.
Light intensity and time of year as well as the natural differences in the concentration of these pigments between species and specimens will have an effect on the results.
Place the leaf and transparency in a frame and then out into the sun.
I found at first just a slight color change of the leaves before them drying out and dying. Test different leaves. Patience.
High light intensity and low atmospheric humidity cause the leaf to dry much faster and consequently, the mid-tones are less or not at all visible.
So it’s important to control the exposure.
f you want to keep the leaf from drying out and dying you’ll need to provide water. You can position the leaf so that the stem hangs out. This will allow you to secure a small bag of water to the stem.
The process can take anywhere from 24hrs – weeks
Preservation of the leaves
The first step is to immerse our leaf for 20 minutes in alcohol to facilitate the penetration of the copper sulfate into the chlorophyll’s magnesium molecule.
Second step. Copper sulphate bath
This would be the equivalent to the “stop bath” in analogue photography.
I use a proportion of 15% copper sulphate in distilled water and I immerse the leaf for five minutes.
Third step. Immerse the leaf for 10 – 15 minutes in running water
Fourth step. Drying. Put it between two sheets of thick cardboard with a lot of weight on them so that the leaf stay flat
Fifth Step. Waxing the leaf. I have not found the optimal wax yet.