The ornamental design for a surfacetreatment for a chair, as shown and described.
FIG. 1 is a front view of the surface treatment for a chair.
FIG. 2 is a side view of the surface treatment for a chair of FIG. 1, the
other side of the surface treatment for a chair being the mirror image of
this view.
FIG. 3 is a top plan view of the surface treatment for a chair of FIG. 1.
The portions of the chair shown in broken lines have been shown for
illustration purposes only and do not form part of the claimed design.