Why do you think they applied an artificial patina, it was to cover up a crappy coin. I'm sure if you removed the "paint" from the coins I posted they would be in the same condition.
I was wrong, 2 of the 3 from the same auction did have an applied patina that washed off with just a gentle wash with water.
I thought that there was something off about their coins, and then I found this thread, thank you for confirming my suspicions that the coins were messed with.
I have several coins from them. All have very artificial patina. They probably do some harsh chemical cleaning in bulk, and after that glue on fine sand, also in bulk. But I keep buying from them, some coins are rare (like one Victor posted) and if I can't get a better example it works for me. Definitely not for everyone. My main concern is that this initial harsh chemical treatment will cause some bad reactions (like bronze disease) and artificial patina will mask it until it is too late to treat. So far I didn't see it, but I don't have them for very long.