FRAME — layer 7 of seven
The Rebate Too Shallow for the Painting
The ledge inside a frame that grips the picture is called the rebate — and its depth is the dimension most easily overlooked.
What the Rebate Actually Does
The rebate is the stepped channel running around the inside back edge of a frame. Seen from behind, it is a narrow shelf — typically between six and twelve millimetres deep — that the picture slots into and sits against. When the depth is correct, the canvas or panel sits flush or just recessed, the glazing (if there is any) clears the picture surface, and the whole assembly lies flat against the wall.
When the depth is too shallow, several things go wrong at once. The most immediate is pressure: if the canvas sits proud of the rebate, the backing board or retaining clips push against the canvas from behind while the rebate lip presses into the front face. On a framed canvas with any impasto — raised, textured paint — that front lip makes contact with the surface itself. It scores a line, it abrades, and over time it can fracture paint at the very edge of the composition. That edge damage is often the first deterioration you see on an old painting.
A second problem is glazing. Glass or acrylic sheet needs its own clearance above the paint surface — at least a few millimetres — to prevent condensation transferring and to stop the glazing pressing pigment flat. A rebate that cannot accommodate both the canvas depth and the glazing spacers forces a choice: omit protection or deform the picture.
The third problem is purely structural: a canvas or panel that sits proud cannot be properly retained. It rocks, it shifts, and the corner joints of the frame take the stress every time the work is moved.
Rebate depth is specified before a frame is ordered, not after. Check the total package — canvas on its stretcher, any liner, any glazing spacers — against the rebate before the picture ever goes in.