To me the washer/round metal disk on the bottom is very obvious - the edge and thickness, though I've been looking at it this way for around 5 years. I can't see putty at all. It's a pretty smooth surface besides the scratches and gouges. There's no rippled putty look.
I've outlined it here:
<img src=http://mywebpages.comcast.net/lonepigeon/dvrotj_bott.jpg>
It's kinda rough, but you get the drift.
The edge is a rust color, the metal is very dull and it dips in the middle form the pressure of being sandwiched between the bottom of the tube and the Kobold bracket.
It's slightly smaller than the tube and the scratches on the top are vaguely circular leading me to believe it was a well worn washer before it was even added.
Why is it there? I'd say the most likely reason is that the previous D-ring bracket was ripped out somehow leaving the bottom damaged. Easiest way to cover that up or any holes in the bottom would be a washer. Granted it might be a little thin for a washer, maybe they just cut a circle out of sheet metal as a patch.
Why is the bottom a different color from the top?
I would guess because the bottom used to have six grips. They weren't just held on by two screws each. There would've been glue as well. I imagine it looked pretty rough after the original grips were gone. The top wasn't modified much since it was built so it's just got the regular wear.
Imperious - There is no Graflex clamp, so the bottom can be positioned whereever.
