The ornamental design for a weldingmask, as shown and described.
FIG. 1 is a perspective view of a welding mask showing my new design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a left side elevational view thereof;
FIG. 5 is a right side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines in the drawing views are included for the purpose of illustrating the unclaimed portions of the welding mask and form no part of the claimed design.