Judith's mention of using a dab of wood ash to clean stove glass inspired me to search for other uses, as we all probably have loads of it which we might just chuck in the bin.
Its seems to be quite versatile stuff, not sure you could sell it, but it has a diverse range of uses as follows; Anyone got any others?
Chicken bath- apparently they like to use it in a dust bath and it keeps down mites, etc.
Slug deterrant- sprinkle round treasured plants to keep veg chomping pests off.
Fertiliser- It contains valuable nutrients like calcium and potash and is good for tomatoes, lawns, and can be mixed in compost. It kills moss on lawns.
If bushcrafting or camping, it makes an effective toothpaste.
Cleaning paste- dab a damp cloth in ash and use on stove glass, aga's, rings left by glasses on wood, and silver.
Pavement treatment- adds grip and melts ice
Pond cleaner- A tablespoon in 1000 gallons helps suppress algae
Making soap- mix with water to form alkaline 'lye', then add to fatty or oily base to make soap, salt hardens it.
One I know very well- add a bit of clay and feldspar to make a beautiful runny green stoneware pottery glaze.
Anyone got any other uses or successful experience of the above ?