That would be a really interesting thing to try...it could function as an unusual stencil or diffuser. I'd say give it a try, experiment, and see what you get! I'd love to see your results when you finish.
Hi Al, yes you can, here's another example
Hi Al: Sure, you can use whatever you want and the paint police will not bother you in the least :) Creativity is great! Let us see what you make!
Hi Al, it's a lovely paint technique, commonly referred to as a dirty pour. Here's a great video that will show you how - https://www.youtube.com/watch?v=anUxUZQVJ40