Wallis Sanded Pastel Paper, Museum Grade, 24 in x 36 inA strong, non-buckling pastel paper ideal for under-painting in any medium, from watercolors to oil washes. Reworking is easy-simply remove pigment with a stiff brush. Museum Grade uses a heavier 100% cotton rag acid-free buffered paper. Both grades have identical surfaces and are coated with pH-neutral archival adhesive, a Wallis proprietary pH-neutral pigmented coating and inert white aluminum oxide grit.