I came across this patent for radiator curtains. The link opens a PDF of the patent with a full description. I've copied the image here, as well. I still don't know what color the canvas should be, but I guess I'll choose a nice brownish tan and go with it.
Re: Radiator Screen Canvas Curtain Patent in reply to namdc3, 01-12-2015 12:37:04
The remnants of the grill curtains I have here may or may not be replacements but they vary from tan to off white (like an old flour sack) I know around here it seemed like an old burlap sack did the trick as there were always plenty to be had.
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