Odd colors on uncleaned after Gringott's boil

[Scotvs Capitis]

It seems to only happen with Byzantine bronzes. I sometimes get a horrible purple pink coin when bare bronze is showing and I boil in Gringott's. I'm boiling these as the first step in cleaning, they are still dirty, but for some reason the patina is gone or spotty or even diseased. Anyone else have this problem?

I don't have a picture of the current batch, but here's on that has a similar purple/pink color on the exposed metal...

[Mayadigger]

Ave!

Scotty,

Can you post a larger photo?

K

[Scotvs Capitis]

Sorry Kevin, if you click on that photo it brings up a large one.

That Byzantine in the lower part of the cup has the purple metal.

That coin had some nice desert sand in it, but alas, it had some nasty bare spots, I decided to put it to the soak. I've got a few more coins soaking right now with a similar purple sheen, tomorrow I'll try to get pics.

[Mark Farrell]

Scott,

I've seen that as well, and also only on Byzantines. I presume it is because of the composition of the coin. I don't know if they can even be called "bronze" or if they are truly almost completely copper.

Other thoughts, guys?

Mark