This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
It is hardly correct to call the passe-partout a frame, as it is merely a binding together of the print, the glass, and the backing with a narrow edge of paper. This simple arrangement lends to the picture when complete a much greater finish and a more important appearance than might be anticipated.
In regard to the making of a passepartout frame, the first thing is to decide as to the width of the mount or matt to be used. In some cases, of course, the print is framed with no mount being visible; but, unless the picture is of large size, it will usually be found more becoming to have one, especially should the wall paper be of an obtrusive design. When the print and mount are both neatly trimmed to the desired size, procure a piece of clear white picture glass— most amateur framers will have discovered that there is a variance in the quality of this—and a piece of stout cardboard, both of exactly the same dimensions as the picture. Next prepare or buy the paper to be used for binding the edges together. This may now be bought at most all stationery stores in a great variety of colors. If it is prepared at home a greater choice of colors is available, and it is by no means a difficult task with care and sharp scissors. The tint should be chosen to harmonize with the print and the mount, taking also into consideration the probable surroundings—brown for photographs of brown tone, dark gray for black, pale gray for lighter tones; dark green is also a good color. All stationers keep colored papers suitable for the purpose, while plain wall papers or thin brown paper answers equally well.
Cut the paper, ruling it carefully, into even strips an inch wide, and then into four pieces, two of them the exact length of the top and bottom of the frame, and the other two half an inch longer than the two sides. Make sure that the print is evenly sandwiched between the glass and the back. Cut some tiny strips of thin court-plaster, and with these bind the corners tightly together. Brush over the two larger pieces of paper with mount-ant, and with them bind tightly together the three thicknesses—print, glass, and cardboard—allowing the paper to project over about a third of an inch on the face side, and the ends which were left a little longer must be neatly turned over and stuck at the back. Then, in the same manner, bind the top and bottom edges together, mitering the corners neatly.
It should not be forgotten, before binding the edges together, to make two slits in the cardboard back for the purpose of inserting little brass hangers, having flat ends like paper fasteners, which may be bought for the purpose; or, where these are not available, two narrow loops of tape may be used instead, sticking the ends firmly on the inside of the cardboard by means of a little strong glue.
These are the few manipulations necessary for the making of a simple passe-partout frame, but there are numberless variations of the idea, and a great deal of variety may be obtained by means of using different mounts. Brown paper answers admirably as a mount for some subjects, using strips of paper of a darker shade as binding. A not too obtrusive design in pen and ink is occasionally drawn on the mount, while a more ambitious scheme is to use paint and brushes in the same way. An ingenious idea which suits some subjects is to use a piece of hand-blocked wall paper as a mount.