Why would anyone want to collect rust? Rust (iron oxide Fe2O3) can be combined with other elements to create fire-by-friction, fire-by-percussion, and even thermite and small rocket propellant. My purpose to collect rust is to make a coal/ember using the fire roll firecraft method.
Steel wool has some interesting properties and comes in different thicknesses or grades from “0” to “0000”, the later being the finest grade. Firecrafters prefer the 0000 grade and will use a 9V battery to touch the steel wool which creates intensive sparks that when combined with fine tinder will create a flame. However, once the steel wool has been lit it will have been consumed as a source of sparks and will not reignite. This is because steel wool when manufactured is coated with an oil to prevent rust and that coating is the part that combusts. So, to collect rust from steel wool it is best to burn off the oil in order to better expose the steel for chemical oxidation.
To burn off the oil coating on the steel wool you can touch it with a 9V battery or use a lighter or in my case I used a propane torch. The steel wool will turn a shade of blue due to the temperature of the burn-off as illustrated in the photo. It will also become somewhat brittle.
After the burn-off you can dip the steel wool into plain water or you can enhance the process by adding salt or chlorine bleach to the water solution then shake it out and lay it down to do it’s transformation over night. In my experimentation I also used hydrogen peroxide (H202) and sprinkled salt on top. Rust was created within hours vs. overnight. When it’s dry, you can rub the rusted areas with a finger while holding the bundle over a sheet of paper so that the iron oxide particles fall below. When finished you can lift the sides of the paper to gather the dust into the center then tilt the paper down to pour the rust into a cup or other container. This can be repeated until you collect a sufficient amount for your purpose. A magnet can be used to separate wool particles but it must be held only close enough for the larger pieces to be withdrawn.
I was able to use my rust to create fire with the fire roll firecraft method and was delighted to add to my firecraft accomplishments. And now you can too!