Evapo-Rust
I thought I'd try it on some street sweeper bristles, that I rescued from Melbourne's storm water drains, that I promised to sideshowmick.
I placed the bristles in a shallow plastic tub upon two perpendicular (rusted) drill-bits so that the Evapo-Rust contacts as much areas of the bristles as possible. I added just enough Evapo-Rust to cover the bristles.
I left the bristles to bathe in the solution for 24-hours. There are no fumes from the Evapo-Rust so it is safe to use indoors. It does have a mild odour -- something like old rubber -- so I used a container witha lid and just lightly covered the container with its lid.
After 24-hours...
After scrubbing lightly with a green Scoth-Brite pad:
I am pleased with the results. I will try it next on my rusty "magic" and "super" picks. It is a little pricey (it is much cheaper in the USA than it is in Australia) but it does do what it says on the label.