Protect your flutes from rust

Vintage metal nose flutes are easy preys for rust. Made of tin plate or low grade alloy, in contact with human grease that coats hands and nose, resting in humid basements... they rust. There are a lot of ways to get rid of oxydation, for instance by applying a coat of mineral oil or a spray of varnish. Another technique is to willingly create a coat of resistant oxyde, which will prevent from rust.
Iron is subject to several kinds of oxydations. The rust [Fe2O3], is the naughty one, because it is formed by irregular crystals which grow (they use more space than actual iron). But other kinds of oxydation may form a regular and hard coat of protection.
Below feature two easy ways of getting rid of rust adapted to nose flutes.

I have a vintage Humanatone which was just lightly rusted, and I wanted to clean it and protect it from future attacks. I didn't want to change much its color, just to fix it in a stable state.

An easy trick for that is to dip the thing in phosphoric acid. This acid transforms the rust Fe2O3 into iron phosphate FePO4, which forms a stable protective coat. OK, but where to get phosphoric acid ? So easy! Coca-cola!
So, I opened a bottle of Coke with a Pfaff Nasenpfeife (High-tech german nose flute which includes a bottle opener (!)), and let my Humanatone dabbling for a night in its Coke bath (yuk!).

Next day, I rinsed the flute (don't drink the Coke!!!) in water added with baking soda (to stop acidic action) and, brushing with a piece of very soft steel wool (000), I got the shiny back. I just sprayed some lubricant (WD40 or so) all over the nose flute (inside included) and wiped it with a paper towel.

More, with the action of phosphoric acid, the different alloy layers had appeared, as if my flute had been forged with Damascus steel!

Another nose flute I have got was seriously rusted when I got it, really attacked, and the method explained above would not have been efficient enough. So, I tried the hard way.

The hard way requires more products, but gives an incredible result. It consists in blueing the flute, exactly as one would do with a gun barrel. That is applying a special oxydizer ("Gun Blue") which will form a very hard black oxyde (magnetite Fe3O4) protective (and beautiful) coat.

First, I performed the Coke bath trick, and the next day removed all the oxyde with a Dremel drill mounted with a polishing disk (plus red paste), then by sanding with very soft steel wool (000) (pic 1). I sprayed some grease remover, wiped the flute with paper towel, and avoided to touch it with my fingers anymore (pic 2). I put some Gun Blue in a (clean:) cat food tin (pic 3).

I applied a nice coat of Gun Blue all over the facing side of the the flute with a paintbrush (no worry, the Gun Blue washes with water) (pic 4) and let actuate during a minute (pic 5). Then I wiped the remaining slimy residue (pic 6) and applied the same coating on the back side.

For sure, I didn't forget to coat the inside, using a Q-tip (pic 7). After that, I sanded the flute with steel wool, medium pressure, not to take all what I did away, but just to egalize (pic 8); I sprayed some grease remover, and re-did the whole blueing process again (one minute application again), and then sanded very lightly the flute with steel wool, just to get back the shiny. Finally, I sprayed some lubricant (kinda WD40) (pic 9).

The I wiped the whole flute with paper towel and Q-tips (for the inside) and got a great result in that, that the patina is still visible, but the flute is well protected (just compare with the original state...)

In conclusion : two methods, the light one and the heavy one, for two very different results. Please feel free to ask questions if something is unclear.