The iris on the left is a watercolor on Ampersand Aquabord and has a background made from scrunched up cling wrap. I've tried this technique in the past and it didn't work well for me but I actually like it in this painting. Of course, there's a ton more work to do on this and I may finish it in gouache instead of transparent watercolor. It's only when you get further along in a painting can you really tell whether a background is going to work or not.
In any case, the background will need some tweaking as work on the foreground will throw off the background. In painting, it's work on the subject, then tweak the background. Tweak the subject a bit then the background's off. The whole painting process involves working back and forth between subject and background. The painting just isn't finished until everything is balanced to the artist's satisfaction.
