Jerry -
You wrote,
"I have often seen old leather holsters leach out a white surface stuff that looks like mold but isn't. It is oils or fats surfacing that had been put on the holster years ago. I have found no good way to get rid of this stuff except to rub it off with a soft cloth."
The dark brown holster you sold me couple of years ago had developed the white surface material you described in your comments above. I took an ordinary kleenex and wiped it off; it did have a slightly greasy appearance. I don't know if it was mold, but it sure fits your description above.
After watching the TV show, CSI, it occurs to me that what we REALLY need on the Forum is a forensics guy who collects Lugers and can analyze materials. Wouldn't that be great ?
Luke