Final answer:
The best way to dry brush bristles so they retain the correct shape is to hang them upside down, avoiding practices like blow-drying or shaking off excess water that can damage them.
Step-by-step explanation:
To ensure brush bristles dry in the correct shape, it is best to hang them upside down after washing them. This method allows the bristles to keep their natural shape while drying without flattening on one side as they might if laid flat on a towel. Hanging brushes upside down also prevents water from seeping into the handle, which can damage the brush over time and lead to the loosening of the bristles. It's important not to use heat, such as a blow-dryer on low heat, or shaking off the excess water vigorously, as these methods can damage the bristles. Surface tension helps maintain the shape of the bristles when they're wet, but as they dry, this effect dissipates, so proper drying techniques are essential.