To make granules, the ash is mixed with water and sometimes with cement to make the paste more stable before it is rolled on a rotating plate. The granules are then dried until their water content is less than 5 percent. This method generates spherically formed units of ash, usually between 4-20mm in sizePitman,R.M. 2006. Wood ash use in forestry - a review of the environmental impacts. Forestry, 79, 563-588..
Granules produced at a given time will have small variations in size. Thus granulation is useful in situations when the ash has to be equally distributed or when using machines that require homogenous ash pieces.
Negative aspects of the granulation method are the difficulty involved and the relatively high cost of the process.