Flat Brushes.—This is particularly applicable to the flat brushes, and the more that most of your brushes will be flat.
You should have both broad-ended and pointed brushes among your flat ones. For broad surfaces, such as backgrounds and skies, the broad ends come in well; and for the small ones there are many square touches where they are useful. The most practical sizes are those shown on [page 28]. But you will often need much larger brushes than the largest of these.
For the smaller brushes you will have to be very careful in your selections. For only the silkiest of bristle will do good work in a very small brush, and then the temptation is to use a sable, which should be resisted. Why you should avoid using the sable as a rule is that it will make the painting too "slick" and edgy. There is a looseness that is a quality to prize. All the hardness, flatness, and rigidity that are desirable you can get with the bristle brush. When you work too much with sables, the overworking brings a waxy and woodeny surface, which is against all the qualities of atmosphere and luminosity, and of freshness and freedom of touch.
Some of the most useful sizes of the more pointed brushes are shown on opposite [page]. There are, of course, sizes between these, and many larger; but these are what you will find the best. It would be better to have more of each size than to have more sizes. You should try to work with fewer rather than more sizes, and, as a rule, work more with the larger than with the smaller brush, even for fine work. You will work with more force and tend less to pettiness, if you learn to put in small touches with the largest brush that will do it. Breadth is not painting with a large brush; but the man who works always with a small brush instinctively looks for the things a small brush is adapted to, and will unconsciously drift into a little way of working.
The fan brush, such as [here illustrated], is a useful brush, not to paint with, but to flick or drag across an outline or other part of a painting when it is getting too hard and liney. You may not want it once a month, but it is very useful when you do want it.