"I know on handboard you're suppose to use gesso. I have tons of white acrylic house paint. Does anybody know if it would make an appropriate substitute?" -- Rachel
The question of whether it's okay to use house paint rather than artist's paint is one that comes up in various forms, but all seem to be motivated by the desire to save money. Personally I think you're best off buying at least students' quality paints, or saving on paint by creating smaller paintings.
In his blog Mark Golden of Golden Paints1 writes: "I can’t tell you how many hundreds of times I’ve heard the question 'Can I use House Paint?' from artists. If you’re asking for my permission by all means go ahead use house paint. ... The opportunity to create and the materials used to create with are limitless. This is a joyous thing. ... But then the next question comes… Is it going to last?"
Golden says: "In no way are [house paints] formulated with any intention to last for hundreds or even dozens of years. I can guarantee that this was probably not in the mind of the formulator. ... The most significant problem with even a quality house paint is that it will begin to develop cracks [some of which] will lead to paint cleaving off of the canvas."
Golden also points out that the hardening of the paint surface means you won't be able to remove a painting from its stretchers and roll it up, or use canvas keys to tighten a sagging canvas.
Also remember that with house paint you still get what you pay for, and the cheaper the paint, the less pigment in it. About.com's Home Repair Guide Bob Formisano says: "most of what you are applying with cheap paint is water or mineral spirits (solvents up to 70%) which evaporate and leave little pigment behind."3
Another issue is that house paints don't perform the same as artist's paints -- they're formulated for quite a different purpose. So don't expect them to mix, blend, or glaze like artist's paints. As Painting Forum Host Starrpoint said in a Painting Forum discussion on using house paint: "If you are experimenting and learning, it probably won't do any harm, but in the long run, you will not be learning to use your tools."
As for durability, if you're just painting for yourself, what you use doesn't matter. Or if you're famous (and arrogant) enough you may believe the preservation of your work is a curator's problem. Or you may be of the opinion that as long as the person buying the painting knows it's mixed media, it's fine. It's a personal choice.
Then again, do you want to be mentioned in history books as a bad example, like Turner is when it comes to the use of pigments that fade?