As a final word on using Evaporust, here are a couple of extra experiments. The first is the lateral adjustment lever mentioned in the previous post. You can see the visual difference between the rust-free region on the left, and the rusty region on the right. This took 2-3 hours.
And finally, a rusty cast iron lever cap. After spending about 4 hours in the Evapo-rust, presto! rust-be-gone!