Cast iron for outdoor use, e.g. garden urns, foot scrapers and foundation valves become rusty and flaming at first, but after a few months the rusting stops. After that, the cast iron gets a beautiful brown-black surface, much like the cannons on the regal ship Wasa. This development can take varying lengths of time and is mainly dependent on the local climate. The new surface layer prevents the iron from rusting further. The method thus gives a new “maintenance-free” surface, but be careful with the rust water at first because it can cause stains that never go away. Therefore, never put a foot scraper on a wooden deck and never place a cast iron urn directly on a stone step until it has completely rusted.
Cast iron cracks if you load it unevenly. Therefore, place the foot scraper on an even surface, e.g. gravel or soil, so that it does not rock and wobble when you step on it. Also, do not leave cast iron urns outside over the winter, but remove the soil from them first. Wet soil that freezes can frost-blast them.
Other iron details, which are not surface-treated, such as door fittings, nails and screws, also rust in outdoor climates. The rusting also stops there after a while and the new surface eventually forms its own rust protection. A doorknob stops rusting when you use it by the grease from the hands stopping the development.
But if you don’t want rusty iron?
Then you paint it with Gysinge’s linseed oil paint. That color is so bold that the iron doesn’t even need to be painted first, you just follow the painting instructions. If you only want a rust protection, but no color, you can lubricate the iron with boiled linseed oil.
