Note-head mass
A music stencil reads first as solid note heads with clear stems, not as thin staff lines or hairline flags. Transfer viability comes from filled heads that stay closed, stems with enough mass to survive print, and dots that sit apart from every neighboring mark. Photo reference and engraved notation show fine grey shading that merges into one band on skin.
Check: Cover all staff lines, flags, and beams. If the bare heads plus stems still read as music at a glance, the foundation is sound. If the read depends on thin staff lines, rebuild head and stem mass before judging anything else.

