HOW DOES OXIDATION WORK?
The drying oil combines with oxygen from its surface downward, hardening as the oxygen reaches each layer. But, more importantly, in relation to the problem of cracking, as oil oxidizes it moves – expanding and contracting during the drying process. The danger arises when a dry and inflexible layer is on top of a still drying and moving lower layer. Anyone who has lived in a cold environment knows what happens to cement sidewalks when the ground beneath expands and contracts during the freeze and thaw cycles of summer and winter: it cracks! The exact same process happens in oil paintings that are incorrectly layered. HOW CAN WE AVOID THIS TROUBLESOME PROBLEM? There are two key components: 1. Make sure that lower layers of paint dry before upper layers; and, 2. Make sure than each successive layer has more flexibility than the previous layer. “OK, OK,” you say, “but what can I do to make that happen?” The answer is the same for both and is summed up by the rule and application of “Fat o
