Forms and shapes
The length of the hairs and above all the form, are the soul of the brush. If they are short then the action is direct, and the brush precise. The diverse forms and the setting of the hairs depends on the qualities of the hair used. The most universal shapes and also the most used in oil and acrylic painting are the "flat" brushes both long and short, the cat's tongue and certainly the round for the details. The oval form is used specifically for the dilute d colours, such as inks, water colour or silk painting,

For fine or larger strokes. The fine point means that it can be used
for detail work but it can also cover large surfaces dependent on
the brush size.

For large and covering strokes or sideways for thin lines. Also used
for washes, mixing colours and smoothing.

Also known as 'cats tongue' for works that are both large and

For pulling and dissolving colours into each other.

For lettering.

For leaf shapes.

For angle and upstrokes.

The choice of a brush is in part subjective, depending on the artists sensibilities, the diverse of the different types of component parts, different forms, dimensions and materials, all re sponding differently to precise criteria.
The handle gives a good grip on the brush and adaption with each type of painting. Traditionally painters brushes for oil and acrylic have long handles which facilitates vertical work and when standing back to view.
The fibres are selected for their specific physical properties: suppleness, liveliness, resistance, fineness and retention capacity.
Natural hairs from animals have a conical shape, with a rough surface. Sable hair is known for it's excellent liveliness, suppleness and exceptional retention capacity and is recommended for ink, watercolour and silk painting, also for works of great finesse in oil and acrylic. The Petit Gris is supple, silky with a good retention capacity and is recommended for watercolour and silk painting. For works with paste paint (oil and acrylic) a pure extra white bristle is preferred for it's firm and robust qualities and natural camber of the hairs. Pony hair brushes, more modest, is traditionally used by children for painting with guache.
Synthetic fibres are monofilament and conical fibres. They are lively with an average retention capacity they are also hard wearing and easily cleaned. They are ideal for oil and acrylic painting. Mixed fibre brushes give the specific qualities of natural hair with the resistance of synthetic fibres and can there for be used for many techniques.