These experiences made me realize that we artists need to take the time and care of label or somehow mark the back of our paintings with pertinent information so that future generations (collectors, historians, relatives) will know this painting is part of our body of work.
For copyright purposes, it's important to sign your name and the date you created the artwork on the BACK of the painting. But I like to add the title, the inner mat opening size, and outer mat size so that if I need to remat/reframe it, I don't have to stop and remeasure.
Two artists told me "I write NOTHING on the back of the painting because I don't want buyers to know that I painted that piece 5 years ago--they'll think it's outdated work". But is that really true? I think collectors enjoy knowing which phase of an artists' work they now have in their possession. Moreover, a purchased painting is often encased in a frame so that the only way to see the back of the piece would be to take the whole thing apart.
Other artists told me "I have a database that contains all the info about each painting" and that's commendable, except that the buyer never sees that database, and furthermore, how do your descents match that database info to an unmarked painting years from now?
From the time I began painting in watercolor around 1990, I have always written my name, the month/day/year I completed the painting, the painting's title (sometimes crossed out when I changed my mind midway through the painting, and replaced with the final title) and the mat/frame size info. I just assumed other artists were doing something similar, but obviously, that's not true. Here's my new mission: I plan to encourage other artists (including my students) to write SOMETHING (anything) on the back of their artwork. It shows future generations that your work had significance to your life as an artist. Think of it as a visual diary of sorts--a rarity indeed in this digital age.