The 1922 Audel's "Elementary Studies in House Painting, Decorating and
Paperhanging" says that beaded porch ceilings are "usually varnished."
However, if the owner preferred paint, one could tint it "light blue
[presumably 2nd choice], cream or any light color specified."

I don't see anything in the text of Moss' "Century of Color" on porch ceiling
colors, but there are little glimpses of a couple of porch ceilings among his
illustrations.

Anybody got anything older than this, or more specific about the reason for
light blue?

Ralph