Wood or cattle dung ash is used for cleaning cooking utensils in many parts of India. The statement that is not true for this ash is :

The statement that is not true for this ash is "if left moist for a few hours in air, it slowly turns acidic because of oxidative decomposition"

In several regions of India, cooking utensils are cleaned with wood or animal dung ash. Since non-metals are eliminated during the burning of the wood/dung cakes, the majority of it is made up of metal oxides and silicates. 

When combined with water, it creates an alkaline solution with a pH of 8 or higher, which aids in the removal of greasy substances from utensils. 

A number of the chemical elements of ash are still present as solids in the water, and these particles aid in cleaning by providing a scouring effect.