Potentially More Hard To Detect Fake Ancient Romans

The center coin is clearly a modern fake I am now used to seeing. The green patina rubs off and it is a perfect strike. So perfect it is obvious it is not ancient. But any non cast coin that is struck on a flan is dangerous of course. In contrast, the four around it are potentially more dangerous fakes to detect. A strike then perhaps an acid erosion followed by a white patina applied that fills into the corroded area. The top left Fausta I rubbed off the white to leave the corroded rust area uncovered. But all four of the outside coins were as white as each other when I received them in a much larger lot of old estate coins. I am only thinking some form of lead oxide is the white but I could be wrong.