...
...I've never found it necessary in cases of light surface rust like you describe. It works by coating whatever surface you present to it and cutting off the oxygen. I have done a few frames that were quite prodigiously rusted internally, and on those, one I sealed up all the holes and the BB and filled it with the non-toxic stuff, Evapo-Rust. Which is kinda expensive, but safe and reusable. And the stopping up all the holes business is a PIA. But that works.

The other few I just soaked in a large container (frame and fork sized...kiddie swim pools work for this) of Oxalic acid, which is somewhat toxic and is absorbed through the skin and concentrates in the kidneys. So wear golves and do it outdoors. It's a PIA neutralizing the acid before disposal with large quantities of baking soda or something else basic.

So for light surface rust this is overkill.