InteriorTerm 9 of 72
Button
top button, crown button
Small button at the top of the cap. Not decorative: mechanically locks the seams at the apex.
Structural function
Definition
The small fabric-covered 'button' at the top of the cap. It is not decorative: it mechanically locks the convergence point of all the panel seams.
It is a hemispherical metal press stud covered with the same fabric as the crown. Positioned at the apex where all panels converge, it prevents the opposing seam tensions from opening the joint over time. Some modern models remove it for a minimal look, but the convergence point still needs reinforcing.