Aged Art?

I really like this aged/weathered abstract art. Does anyone know how to achieve the look? Do you know of any good information resources?
via jen bradford
update- I posted this question on Curbly and here are the 2 answers that I have received so far;
"You'll have to do some experimenting, but I've been told that after you paint the base color, wait for it to dry, lightly sand it, and then go over it with a coat of stain in whatever tone you want (gray, brown?), and wipe it off after a minute or so, and it will give the object an aged look. It doesn't matter if the paint is water or oil based. The stain will mostly be confined to the tiny grooves from sanding. I haven't tried this myself yet, and you will have to tweak it a bit to get the effect you want, but it should work."

"You could do this yourself. Buy some pre-stretched canvases in the sizes you want, and sort out your colors. You can paint the color blocks using acrylic paint. Put it on nice and thick, if you want some texture to it. The "aged" effect comes from a series of glazes over the top. You'll see a "glazing medium" near the acrylic paints at your favorite art supplies store. Mix that glazing with just a little color, and wash it over the top. Remember that the colors you mix into the glaze will affect your base colors. Often, using complimentary colors will have an interesting effect. Use several layers of glaze in varying shades to give it real interest. You might have to experiment with it first to get the colors you're looking for."