For most uses, a high-quality synthetic-bristle brush rivals a natural-bristle brush and costs less, sometimes only half as much.
You can take matters into your own hands, too, by showering with a stiff, natural-bristle brush; like moderate-pressure massage, this stimulates pressure receptors under the skin, Field says.
Top-quality, natural-bristle brushes give marginally better performance with alkyd-based paint, but because they absorb water and then become floppy, never use them with latex paint.
Use a natural-bristle brush to apply oil-based polyurethane, and a synthetic-bristle brush for water-based polyurethane.
However, besides being expensive, natural-bristle brushes can be used successfully only with oil-base (alkyd) paint or other solvent-thinned finish, which contains no water.
Since milk paint is a water-based paint, it should not be applied with a natural-bristle brush.