If you will recall, after cleaning the 3 little panels, I did a test of trying to apply a wash right on the unprimed aluminum. Not surprisingly, there was little to no adherence so I wiped that panel clean and applied straight lead white paint as a primer of sorts. The other two panels got my normal acrylic gesso.
Normally, on my wood panels, I use 3 coats of acrylic gesso to get a satisfactorily white surface. The aluminum panels required 4 minimum. For some background, I do not sand between coats. I like the natural brushmarks and do not feel a flat surface is necessary for how I work.
3 panels ready for paint. Note the upper left one, this is the one which was primed with lead white paint. It only got one coat and will painted on just like this.
A fellow artist I know from the great white north of Finland had some wonderful photos of some snow and fog which I wanted to paint so I chose one of these small panels just for that purpose. I gave it a nice wash of pink and then proceeded to paint. I really did not note any differences in working on this surface versus a wooden panel. The paint seemed to move similarly, which is what one would expect, both surfaces being relatively smooth compared to canvas or linen even. All in all, I am quite happy with the result.
Next time...weight concerns.