I am wanting to make a reasonable quantity (10-100g) of iron powder that I can use to visualise magnetic fields (by putting the powder in a thin layer between two transparent materials). The finer the powder and more consistent the size the better. Ideally I would like a particle size 1 micron or smaller.
I've used a very fine grit sandpaper of about 2000 grit and this had a great result but took an eternity to produce.
I also made iron powder via electrolysis with an iron anode/cathode, in an aqueous solution of iron sulphate. I used an old repurposed PC PSU to supply 3V and however many amps the PSU could output for the electrolysis.
This produced some iron flakes which seemed a bit too large for what I wanted but it made a lot of iron particles quickly and with little effort.
Main question: Do you know of any good processes I could use to make fine iron particles using electrolysis or another chemical process?
Related side questions: What's a good liquid medium for suspending iron particles?
Is iron the best material to use for a viewing magnetic fields? How does it compare to other materials like Cobalt,Nickel,magnetite,Tungsten (Paramagnetic), NdFeB dust, etc?
A magnetic field viewer with silvery white particles (as opposed to black particles) could look nice. What might be a good way to turn the magnetic powder more silvery instead of black?
Is there a way to produce a good quantity of very fine, needle-like rods of iron? This could also work well for visualising magnetic fields as I believe the 'needles' would want to align to the magnetic fields.
I appreciate any help you can offer me!