I often paint in urban areas with people around, so I’ve gotten used to chit-chatting while I paint. But teaching while painting is a different animal. Watching someone paint doesn’t always make for good entertainment, nor is it automatically informative. It’d be great if every piece of art was created in a flurry of hot passion and joy like in the movies, but in reality, art making involves many long, silent pauses. A lot of standing back and thinking. Then there's the backtracking, second-guessing, editing, and inner voices speculating about whether I’m a fraud and really suck and what I’ll make for lunch.
A good demo, then, should reveal the thinking (the constructive parts), not just the doing. You will rarely see a canvas come to completion, but you should expect the artist to articulate why they make the choices they do. Years of experience can render some impulses second-nature, but a good demo artist will at least attempt to put into words where those impulses come from. If I get wrapped up in where I’m going with a painting, or go too far with a too-specific tangent, it's easy to miss big things people aren’t getting, so I encourage people to bark out questions as often as needed.
I also like to involve the audience in the choices I need to make. Is this too dark? Should that be more chromatic? Do these brush marks call too much attention to themselves? Is that shape too far to the right? I want you to see that the path isn’t always clear. There are judgement calls, choices to be made, and there is never only one right answer.
To Frankenphrase Pat Benatar and Axl Rose: Painting is a battlefield. Welcome to the jungle!