Hello!
Although these encrustations look at first glance like those easy ones - ready to chip off - they persisted all gentle cleaning attempts so far.
Alexandria in
Egypt, 181-171 BC., Ptolemaios V.
Epiphanes,
Obol,
Svoronos 1238.
The visible layer is a mixture of sand, earth and dirt.
This is cemented by a (the second) layer of brown and then green-blue oxides to a smooth and fortunately non-corroded bronze
patina surface.
So far i tried boiling in DW, soda solution and soaking with oils for a couple of days.
With high pressure on the tip of a
sharp steel blade i can chip off very small particles.
But the danger of slipping and causing irreversible damage is high.
Maybe someone has more experience with such a "bane of the Pharaohs".