I once tried to make iron fakes to make a kind of gunpowder that sparkled like sparklers do, so I got some iron and as anyone will know after you have cut the metal you are left with a pile of iron filings - perfect I thought, so I tried an angle grinder and this didn't work. Afterwards it hit me that holdon as you cut the metal, it spakes so its already oxidised and its hardly going to want to burn again... LOL.. Hmm well I was young then haha.