Originally Posted by F&J
Don't use muriatic on cast iron...period. If you soak a cast iron part for a while, it will look like the moon...only the craters will be deeper
That is what I meant earlier when I said "especially cast iron" because it is slightly porous and will retain some of the acid. I guess technically it may not actually be porous but the irregular micro-grainy type surface will be just as bad.