That’s a great question. Thank you.
A Soft brush is made out of Rabbit or Goat hair, holds a lot of water and can come in many sizes. The disadvantage is that once you complete a stroke with it, the brush has to be re-loaded as it will not keep it’s shape.
The primary uses for a Soft brush are:Painting Birds breasts with one stroke.Swirling the brush and allowing it to split to form a Horse’s main and tail.Doing the same to create a Goldfish tail.Painting the ‘Culm’ or stalk of the Bamboo.
A Hard brush such as the Large Orchid Bamboo has great resilence and you can do more than one stroke with a single loading of the brush. For example, you could do four or five Bamboo leaf strokes with one loading. Hard brushes also come in many sizes from a Fine Detail on up and they are made of Wolf or Deer hair.