oil or water base?

Question

How can I determine if oil or water base paint was used on household walls

Answer 1

Walls should normally been done with water base paint. If it is 'non glossy' paint and I mean powdery, it is water base.

If you are talking smooth surface: Take a chip (at least the size of your fingernail) of paint from some place and put in hot water (not boiling but close).
If it goes all gooey or even dissolves it is acrylic paint, if it stays pretty much the same, firm, it is an 'oil base' paint.