Hello, All. I left these in the tumbler too long, thinking they were steel, with a coating of dark crud. Tuns out it was tarnish, and what I am guessing is brass , came to a high polish. These are Mohr's Patent Tubing clamps, for lab use. Does it make sense that these are made of brass? Definitely non-magnetic, could they be plated? I would think that brass is not strong enough for a spring clamp, even this small? Regards, Lou