The chlorophyll printing process works by letting a leaf receive an extraordinary amount of UV light to force a pigment change while the leaf is alive. There is very little information about this process on the internet and much is inaccurate. Guide yourself by this blog to avoid getting confused.
Most leaves have a variety of pigments that can absorb and release energy from a wide range of wavelengths, these are chlorophyll pigments, carotenoids and anthocyanins. Pigments capacity to absorb and dispose of energy is crucial to keep plants’ photosynthesis mechanism undamaged.
Anthocyanins do not intervene much in photosynthesis so they are irrelevant to us.
Chlorophyll pigments, the green ones, absorb UV light and reflect back to us green light, and can convert light energy into chemical energy, these are the main pigments intervening in the photosynthesis of the plant. However, they do not help to release any energy excess, so if the plant receives too much UV light, only carotenoid pigments can intervene.
Carotenoid pigments absorb less UV light and more violet and blue-green light. They can reflect yellow, orange and sometimes red light to us. Carotenoids are present on plant leaves, but we often don’t see them because chlorophyll pigments are more abundant, therefore masking any other tone. Carotenoids play an important role in absorbing light when there is less UV available (autumn), but they also play a crucial role when there is too much UV available.
When we leave a plant or a leaf in full sunlight (like when we forget a plant by the window sill), it is receiving a huge amount of energy, if that is not handled properly, it can damage the photosynthetic machinery. Carotenoid pigments have the capacity to dissipate any energy excess as heat as they are able to convert chemical potential energy into vibrational energy. In order to keep a healthy UV diet and preserve the photosynthesis mechanism the leaf changes its pigments and gets rid of the energy excess. It is a survival strategy. When we leave plants by the window and we see them turning lighter green or even yellow, this is not because the plant is drying or dying, it is because the plant is forcing a pigment change to cope with the overdose of sunlight.
When we are using the chlorophyll printing process, we are forcing this pigment change. We are not letting a leaf drying out, that would result in brown, curly and very fragile leaves instead of any print.
