There have been a couple of comments about lead being absorbed while cleaning leaded windows.
Some were from a guy who worked with lead, upshot is that it is not really possible to absorb sufficient lead from window cleaner to suffer even the slightest risk to your health.
You simply are not going to be in contact with it for long enough.
My way for cleaning leaded windows though?
A very light spray just as Roger said, but a microfibre for me...A DRY one
The mist of spray on the glass is absorbed by the dry microfibre (or scrim) and this lifts off and polishes the glass.
Use of the damp scrim and a barely damp scrim is fine, but getting into corners means a slight pause in motion, and this can leave marks.
I'm not saying it can't be done (I used this method myself many years ago) but using that method takes a great deal of skill to get it right.
A dry scrim, and to a lesser degree a dry microfibre, if used on glass that is too dry will do a poor job, lot of dust left behind and the dirt only moved around and not picked up, but when the glass has enough of the solution on the glass it comes up fine, and it doesn't take so much skill as the other way to get a good result!
Regards,
Ian