Washes can be brittle and fragile paint films because of this.

First, the paint is softened; the second is to dissolve the paint film.

Lead white paint dries relatively quickly to form a strong, flexible paint film.

Zinc white dries slowly and creates a relatively inflexible paint film.

Since the solvent has weight the dried paint film will weigh less.

The mobile phase may play a role in plasticizing paint films, preventing them from becoming too brittle.

A smooth or textured paint film can be produced.

It is volatile and does not become part of the paint film.

Additionally, the rules of "fat over lean" must be employed to ensure the paint films are durable.

In addition the overuse of megilp media (or any medium for that matter) tends to create weak paint films.