Rule of Thrum

This late 16th or early 17th century drawing shows what could be a variety of thrum caps in different shapes and colors. This is relatively unusual, as most paintings display only a single type.

Note that the gentleman on the right side seems to be wearing a skullcap-style thrum cap that has come slightly askew, which is very common in depictions of that type.

Found in the Städel Museum collection.