I can't speak for ORD, but in the airports I've been to recently, the signage is completely ineffective.

The signs I have seen are no larger than an 8.5" x 11" sheet of standard size paper. The words stating that the technology is optional are, most certainly, not in a bold typeface. In regards to the typeface it appears to be a standard 12 pt. font. The problem with choosing this size font is that, again in the airports I have transited, the signage is either not in an appropriate place, or placed in such a manner as to be unreadable by the people approaching the WBI machine.

Case in point - I have seen signage for the WBI on the stanchions for the line leading to the ...drumroll please... WTMD. Now, what good does this signage do there? I have also seen signage placed on a WTMD/WBI shared line where the signage is placed in such a way so as to be at the backs of the people approaching the WBI. Just curious, does TSA believe that terrorists have eyes in the backs of their heads? That is the only explanation for this poor placement of obligatory signage.

Sure, the signs are there. Sure, the signs are prior to the machine. Where TSA has failed, again, is that while living up to the letter of the law, they have completely ignored the spirit of it for their own apparent purposes.

I welcome you to post a picture of the sign. If allowed to take pictures I will show you where the signs are poorly placed.