Other paper, paperboard, cellulose wadding and webs of cellulose fibers cut to size or shape; other articles of paper, pulp, paper, paperboard, cellulose wadding or webs of cellulose fibers (not enumerated). 

This type for frame would have a paperboard base with a paper wrap cover.

Note: the paper wrapped MDF frames are coded as 4414.00.0000, wood picture frames, duty: 3.9%