I was thinking about Dave Weinberger’s post as I was flipping through a bit of ephemera I found tucked inside my newly acquired copy of Commercial Photography of Today (1914) by Geo. W. Hance. It is a booklet on filters, Color Plates and Filters for Commercial Photography from Eastman Kodak without a date, though it might be dated from their recent purchase of Wratten and Wainwright mentioned in the frontis. Their advice, though targeted at photographers, seems appropriate in a political context. I think we need a “B” filter.
If it is desired to have a colored object photograph as black, it must be photographed through a filter that will completely absorb the color of the object. No rays of light reflected from it will then reach the plate, and as a consequence, it will photograph the same as though it were black. Suppose, for instance, we have to photograph the American Flag. If we use a red filter the blue will be absorbed and will photograph as black, but the red will pass on through the filter and make almost as much impression on the plate as the white, so the red stripes would scarcely show in a print from the negative. (Fig. 1) Of we use the green “B” filter which absorbs both blue and red, we will get both the blue and the red completely black. (Fig 2)