In his fine article, Bill Koenigsberg, advances a theory about the
thickness of cloth used by Aeolian on their late style Duo Art
regulators.  I think Bill would be hard pressed to prove that the
use of the heavier cloth actually slows the rate of movement of these
regulators sufficiently to be discernible.  It's my guess that cloth
friction would rank well below the 1% level in the sum of all forces
acting on the regulator.  In any event, any thing that impedes the
regulator movement would have the affect of making them more prone
to "overshoot" the desired vacuum level.

My cursory observation is that Aeolian just made this device more
robust, and thus used a stronger cloth.  It certainly was a vast
improvement over the earlier style.

Bob Taylor
Missouri