As a teacher of Botanical Art I am often asked about painting leaves. Leaves are probably the most important thing a botanical artist MUST master. In order for the painting to come to life, the leaves must look natural and have the proper venation. Here is a leaf in progress:
I start by mixing my colors and deciding where to drop the color. I usually drop the color right along the vein. After the color has been sculpted I let the paper dry. I then use a chisel brush to lift out the veins.
I use the pencil line to decide where the shadow is going to be cast and then lift above or below the line… not directly ontop of the line, this is very important. If you try to lift the pencil line, you will get a muddy mess! The paint will lift and the pencil line will create a shadow. It acts as a guide and also makes a depth at the same time.
Another fun thing to do is to use a paint that will granulate to produce insect marks and crumbly bits. I think that it gives the leaf character.
What is your experience with lifting veins? Is it easy or difficult. Let me know what you do.