When I was a kid, I remember this refreshing lemon smelling that I was coming back coming back from school. My mother or the cleaning lady would have just washed the floor with this black soap.
This soap is 100% natural and biodegradable. It is made with water (where ashes have soaked), potassium and olive oil which are boiled together.
You actually can use the black soap to wash EVERYTHING: it makes the spigots shining in a few seconds, it cleans limestone sediments bathroom, the fat traces in your kitchen. It nourishes and protects the floors, the tiles, linoleums, etc.
I am myself using it for everything: cleaning the shower, the toilets, the floor or the kitchen surfaces and fat pans. Every week!
A recipient costs less than 5 euros for more than a year of use (including all the uses listed before). And be careful, the black soap is very concentrated, so, only use a tea spoon of black soap is sufficient in a bucket of warm water (for the floor). And don’t rinse it! Or a little bit directly with the sponge for the kitchen and bathroom and rinse it.
You can also spray the same soapy water in the garden (on the leaves after the water got colder), it will replace dangerous chemical insecticides and scare away spiders, aphids, etc.
***This is a typical useful grandmother tip. You find the black soap at the organic supermarkets (ie. in the Netherlands) or at the normal supermarket (ie in France) in the cleaning section. Some black soaps are artificially enriched with not natural additives, check the ingredients.