As I have mentioned there were certain problems with commonly recommended acids to treat paper, calcium oxalate as one of them. Although, it can be dissolved to some extent in EDTA, insoluble remains adversely effected prints with thin hot pressed papers.

I have no clue if it can be used as clearing agent. The information on the internet points out that sulfamic acid is iron ligand, it forms water soluble calcium and iron(3) salts, if this helps.