This made me wonder, what about Star San and PBW?? I received this response from Ryan Alcala at Five Star Chemicals… “When it comes to our products they are compatible with stainless steel, glass, and rubber. They are not however compatible with softer metals like copper and aluminum.”

So the “magnet test” is to take a magnet to your stainless steel cookware, and if it sticks, it's “safe”—indicating no nickel present—but if it doesn't stick, then it's not safe, and contains nickel (which is an austenite steel).

Starship's mostly-silver appearance comes from a type of non-corrosive alloy called 300-series stainless steel. It's the first time someone has made a rocket from this material since the 1950s.