still getting flash rust on copper patina????

[cbassjr]

I am still getting flash rust on my copper patina. I use muriatic acid to clean good then baking soda. Am Buffing and polishing steel but can't seem to get a really nice copper finish. I'm a newby and have read several of the posts here. I did have some skipped cutting issues also. When I read an article about the cutting issue I read about the steel quality. I was cleaning a piece a couple of days ago and noticed a stamp on the metal made in Mexico. I'm thinking my metal seller is buying on the spot market and wondering if this is like the Chinese metal issues I've been reading about. Any thoughts would be appreciated.