I recently completed two paintings of the same–exact same–subject. These self-portraits were started at roughly the same time and both recently finished.
Why two paintings on the same subject? Technical reasons! No, really. I wanted to compare two mediums and determined the best ways was to test them on the same subject. The smaller one was started with a mastic-based medium. I’ve used mastic-type mediums in the past and wanted to see how it compared to the copal-based medium I normally use.
I did not like the mastic medium and, instead of abandoning the painting, reverted to my normal medium half-way through. So both were done with my fast-drying copal medium. Because I confirmed the superiority of my normal medium, the test was successful.