PDF? bearing material

I remember reading in Sky and Telescope about different altitude bearing materials, and one material that came up was I believe called PDF. I was wondering if anyone has used this material on their own scopes (as opposed to just testing it as in the article "in the lab"). What do you think about this stuff, and does anyone have that article where they can give me the web site of the company that makes it? Thanks!

Evan

I remember the article, Evan. I think it was "Improving Dobsonian Motion", by Martin Lewis, in the October 1999 S&T. He tested a whole bunch of materials, looking for a combination that gave best results when you only need to nudge the scope a little bit, like at very high magnification when it's all too easy to overshoot. I remember it being like a Teflon fabric, and it had lower "stiction" than solid Teflon.

Martin also has a more recent article "Better Dobsonian Bearings", in the October 2003 issue. Curiously, I don't remember reading that one, though.

I'll try to remember to look them up when I get home.

Doug