If you listened to the Studio 360 segment that he produced about this project, you know that Sol LeWitt works are accompanied by a certificate. A work isn't authentic unless it's documented. In the podcast, Mark explains what happens in the surprising buying/selling process, as the work can't actually be packed up and shipped to the new owner:
With the big back story to this wall drawing, I somehow forgot to tell you a very important and timely detail: Mark Phillips, who spent about six months recreating Sol LeWitt's Wall Drawing 1211 with colored pencils in his bedroom, may be moving out of his apartment. In need of more space and less noise, Mark has been looking around for a new home -- perhaps one with nice, smooth walls. This much is true: he can't take the beloved replica with him. So what will become of it?
"You pay whoever owns it for the certificate, and then they actually have to paint over their drawing. Only then does the LeWitt estate send over their trained assistants to draw the new version on your wall. Theoretically there's a one-to-one ratio between drawings and certificates."
If you lose the certificate, well...
So, of course, there's no certificate to Mark's work, but he will have to paint over it before he moves (likening his landlord to LeWitt). "And yes," he says, "I do think I'll have another go at this drawing in the new place, especially now that I've mastered the technique and learned a couple secrets from the Sol LeWitt installers. I might try something new, though." Hmmm.
In 1968, when it came time to destroy the first wall drawing at the Paula Cooper Gallery, where the first drawing was exhibited, the task landed in the hands of owner Paula Cooper. But she couldn't bring herself to do it. LeWitt painted over it himself.