This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
Plate Sinking Mounts. - Modern ideas regarding the dress for the photographic print have so revolutionized the method of mounting that for even the ordinary class of customers light-weight cards with large margins surrounding the print, or prints made on heavy-weight papers, printed with white margins, are preferred to old-style stock cards. This being the case, the photographer with business instinct must take it upon himself to adopt the simplest and most inexpensive method of preparing such mounts or prints to suit his own trade.
The embossing of the mounting card, as well as of the print itself, enters into the process to such a degree that the most simple method is the one to adopt.
A few sheets of good-quality 10-ply cardboard from which to cut small cards to use as blocks, a square, and a toothbrush handle, or similar instrument, are the requisites.
Lay the square on a convenient part of the work-table. Then rule off a series of lines at right angles, 12 to 18 inches long and 1/2 inch apart. (See illustration No. 7a.) Now, for a 7x9 plate sunk opening you should use at least 11x14 thin card mounts. This will give you 2 inches margin on sides and top, and 3 inches at the bottom.
First, cut a piece of the heavy cardboard 7x9 inches square. This we will call your card block. Lay this card block on the table, having the top and one side correspond to the inner lines previously drawn. To hold this card block in place, insert two thumb-tacks, one at the top and the other at the bottom. The sheet of light-weight mounting board, having been cut the proper size, should now be laid over the card block face side down and adjusted to the lines, measuring 2 inches from top and side. This will bring your card block in proper position under the mount. By adjusting the mount to lines, the margin will be absolutely accurate. Now, take the round end of a tooth-brush handle, or similar tool, and with slight pressure locate the card block underneath the card mount, by sliding the end of the tool over the card mount until you strike the side of the card block; then, with some pressure,
Illustration No. "7a follow this edge all the way around. Turn the card mount face side up and you have a plate sunk mount.
Plate Sinking Prints. - To plate sink a print first measure the print within the margin. Say this measures 5x7 inches. Then, in order to allow for a 1/4 inch margin on top and sides, and a 1/2 inch margin at the bottom, cut a square card 5 1/2 x 7 3/4 inches. Next, provide a transparent tissue paper the full size of the print, including the white margin, and lay the card block in the center of this tissue, and, with a pencil, outline the size of the card block on to the tissue. Next, place the tissue which contains the outline of the card block over the print to be plate sunk, adjusting the lines so as to give the proper margins around the print. With this done, next lay your card block on the tissue, within the lines; then, catching the print, tissue, and card block, holding them firmly together, turn them over with the print on top but face side down. Then run the plate sinking tool around on the back of the print, following the outline of the card block just the same as when plate sinking the mounting card.
Different size card blocks should be made to suit the different size openings or plate sunk centers desired. The size of each block should be plainly marked on the face to enable you to readily select from your collection the size required.