The advantage of flat storage is that, if boxed carefully, the papers will remain flat and uncreased. The use of acid-free folders or envelopes within the boxes will prolong the life of the papers. Very large items such as maps are best stored flat in drawers in acid-free folders. If necessary, such items can be folded, although this is only recommended for materials which are used infrequently, as repeated folding and unfolding will lead to deterioration along the folds. Avoid making multiple folds which intersect, as these will eventually wear holes through the paper at the points of intersection.
Many safe products are available for the storage of paper materials.