Pinit Archival Foam Board Backings for HALF SHEET POSTERS. 22 x 28" images. .1875" thick (3/16"). All white. Acid & lignin-free. Buffered. Indefinite Storage. SKU: KHSPFC (0)No Reviews yet Add to Shopping Cart Details MUSEUM GRADE Half Sheet Poster Backings 22 x 28" .1875" (3/8") thick Foam Board. Acid-free & Buffered Board. All white. Indefinite storage. Details Back DetailsMUSEUM GRADE Half Sheet Poster Backings 22 x 28" .1875" (3/8") thick Foam Board. Acid-free & Buffered Board.All white. Indefinite storage. Reviews 0 Back Ratings & ReviewsNo reviews availableBe the first to Write a Review