Oxalic acid (a white powder) is an excellent rust remover. Mix powder with water and let your object soak. Check it occasionally as it soaks. You'll be pleased.
KS
Oxalic acid that's whats in the rhubarbs...Me and a friend
was going to clean up one of his Holly's and he said.. when mom
make rhubarb cream in aluminium pot they get all shiny inside lets
boil it in rhubarbs. So off we go picking some rhubarbs and chop
them up mix with water and a holly in his mothers pot and start
boiling. Everything seems fine till his mother came home. What are you
guys doing? O just some Rhubarb cream

my friend replied
Ohh but its to thin you Ned potato flour in it let me help you and she
took a spoon and started stirring

.....that's when we ,the Holley,
the pot and the rhubarbs was thrown out of her kitchen

We still laughs att that today when we remember it