I sometimes use oil based enamel paints from a hardware store to make my paintings. Of course some people have asked me if it's a good idea. Here are a couple of the videos I made about it and some correspondences I've had with other artists and the questions they've asked.
My question to you (as it seems you also use enamel paints in your projects, can I use the hardware store bought enamel paints directly on a standard cotton stretched canvas?
I think as long as you are working on a gessoed canvas that isolates the fibers from the enamel paint you should be okay. Franz Kline and Jackson Pollack both used oil based enamel paints to make their paintings. Kline's work is holding up really well but Pollack sometimes didn't put a gesso coat down so some of them are deteriorating. There's actually an anecdote about Franz Kline's agent replaced his paints with artist's grade paint and Kline threw away the newer more expensive paints and went to the hardware store for more oil based house paint.
I noticed you used both canvases and masonite boards for her paintings. Doing some google searches, there are some warnings about using Enamel paint on canvases.
I think they should last about a hundred years or so before the paints fade and or interact in some way with the surfaces. I'll be dead by then so I'm pretty confident that it's okay!