Working from both the front and back of the canvas was essential for mending the tear in Seated Girl: thread alignment could only be accessed from the reverse, while the painted surface required precise positioning from the front. To avoid flattening Villon’s original tacking margins and plier marks by mounting the canvas onto a stretcher, a temporary non-adhesive working support was developed.

The canvas was placed face down on a rigid 4 mm plexiglass sheet, providing stability during handling and allowing the painting to be safely flipped without distortion. The plexiglass's transparency enabled visual monitoring of the paint layer during treatment without flipping the canvas. A cut-out at the tear location allowed direct access from the front. When working on the recto, the original folds were preserved using a custom foam support.

Magnets were used only during flipping (for a maximum of ten minutes at a time) to secure the canvas to the plexiglass. Prior testing confirmed that magnets on the tacking margins (where no paint is present) caused no deformation. Each magnet was cushioned with blotter and soft non-woven fabric to avoid indentations. Eight magnets were used in total. A schematic of this system is shown. This approach proved to be an effective and minimally invasive solution.