After Hans Scherell, and before Klever, Scherell's Shaftol was offered by Andrea Berger-Scherell of Mainz, grand daughter of gunsmith Oswald G. Scherell. So I beleive Hans Scherell was Oswald's son, who seemingly emigrated from Berlin to Mainz after WWII.
BTW I bought a couple of containers of Shaftol at the IWA Nurmberg International Arms Fair maybe twenty years ago, from an older gentleman in his 70s I would say, and now I'm quite confident that I was in fact dealing with Hans Scherell himself. I still use that same Scherell's Schaftol to good effect.
- Jani