To create interesting prints of plants, I always start by brushing paint over the surface of the gelatin plate. In this instance, I used Setacolor Transparent paint in green and Jacquard Lumiere in bright gold.
The plant is then placed onto the painted surface in the desired location. This will make the first print. Lay a sheet of fabric or paper over the paint and plant material. Press gently with your hands - moving them around to make sure all exposed paint is transferred. This first print will look like a stencil print - with the plant creating the stencil.
Next, gently lift the plant material away. You will see an intricate imprint from the plant material has been left behind on the gelatin plate. This is the image used to create the second print. After the plants are removed, lay another piece of fabric over the gelatin plate. Smooth it carefully with your hands until you think all available paint has been transferred from the gelatin to the fabric. Then, lift the fabric away and set it aside to dry.
Lya, I think the gelatin sheets can be reconstituted in water in order to make a plate for printing. I am not sure what the proportions should be, but I think you should try a small amount - maybe on a paper plate or something - use half the water you would normally use for edible gelatin. I think that should work. Let me know how it goes if you try it!
Lisa, I do reuse the modeling clay. The soft gelatin can be washed away or it can be left to dry and then the flakes can be discarded.