The bloggers on the Brooklynian Crown Heights forum got me thinking about the remaining hand-painted signs in Brooklyn, of which quite a few can be found in the outer neighborhoods of the borough. I came across this excellent specimen out on Pitkin Avenue and Doscher Street, a block east of the Euclid stop on the A-C.
These signs, though individually crafted, seem to adhere to a similar template. The paint appears to be oil, probably standard exterior paints, and the signboards are sheet metal (though I don't know what sort). As one poster on the forum noted, this makes them targets for scrappers and prevents their preservation as they are gradually replaced.
What I don't know is whether such signs were painted by the merchants themselves, or ordered up from local shops that specialized in the art. Signage business still exist in Brooklyn, of course (stores still have signs), but the product has changed so thoroughly that I doubt they would have any connection to the hand-painted products of yesteryear. What would be great would be to find an old hand to describe the process firsthand and point out a few of his products that still remain.