e/Tightening key

Information
has gloss	eng: Tightening Key is a small wedge or block inserted into the slotted inside corners of a canvas stretcher frame. The key is tapped in to expand the stretcher bars slightly, tensioning the canvas. The keys can be used to re-tighten the canvas as it relaxes naturally over time. Tightening keys are commonly made in plastic or wood.
lexicalization	eng: Tightening key
instance of	c/Painting materials