The stretcher frame (in the 19th century also called key frame, blind frame with keys or blind frame with wedges) is a slotted, by wedges enlargeable (auskeilbarer) frame for re-stretching the painted canvas (canvas painting), or is used for high-quality inkjet prints as a base frame.
The entire image creation of a canvas painting, from priming to varnish, takes place on the stretcher. It is believed to have originated in the French-Dutch region. The stretcher frame is a further development of the stretching frame. Some old stretcher frames show traces of work (wooden nail holes) from which it can be concluded that they were formerly stretching frames, which were later reworked into stretcher frames.
Source: https://de.wikipedia.org/wiki/Keilrahmen
