While protecting works of art and valuable paper items, such as diplomas, with acid-free folders and archival-quality boxes may be appropriate for storage - it is neither convenient nor safe for items you wish to display.
One of the best ways to preserve your art for the future while being able to view it is to mat and frame it using conservation-quality materials. You can bring it to a professional or do it yourself. If you choose to have a professional do the work, be sure to choose a reputable framer and specify the materials used.
Whether you or a frame shop frames your art, all mats, backing materials and adhesives should be chemically stable and acid free. Adhesives that come in contact with artwork should be permanent but reversible. When handling your art, use cotton gloves to keep from soiling the paper.
Here are some basic guidelines;
When choosing a frame, make sure it has a rabbet deep enough to accommodate the thickness of a mat, backing board and glazing material. For backing board, use 100% rag content mat board, double-walled plastic board like corrugated polypropylene or material with paper surface layers and a central foam layer. Never use Masonite, corrugated cardboard, wood or other materials that are not acid-free. Seal the frame with adhesive tape to keep out dust and pollutants.
One of the safest methods for protecting photographs and prints is to mount and mat the item using 2 pieces of archival quality mat board. The general rule is for the backing board to be sturdy enough to support the piece while the top or "window" mat should be thick enough to protect the item from any surface damage. When preparing a print for display, use a minimum of 4-ply mat board for the window mat. This should be thick enough to keep the surface of the print from touching the glass in the frame. Some prefer 6 or 8 ply board, to enhance the overall appearance of the print and also to provide an additional space between the print and the glazing. When preparing a print for storage, 2-ply is sufficient and also allows more space to fit additional matted prints in the storage box or drawer. It is advisable to cover the surface of the print with an interleaving tissue or paper before stacking.