A window mat consists of two parts, both cut from acid- free board: a backboard and a window. Four-ply board (made from four layers laminated together) is normally used; larger objects may require double or triple mats or thicker board, such as eight-ply. The backboard need not match the window; a less expensive board can be used as
long as it is of archival quality. They should be the same size and they should fit in the frame snugly. Cut both the backboard and the mat blank (window board) to size at the same time. If you have a mat cutter, the cutting head can be set to cut at 90°, and the boards for all the art can be cut at one time.
Many institutions use modular or other reusable frames in a few standard sizes (for instance, 14" × 18", 20" × 24", 22" × 28", 28" × 40") rather than having frames made to the size of each object. The borders of window mats have to be calculated so they cover the edges of the art and extend to the edges of the frame. This is different from the way matting is done at a framing studio, where the size of the mat and frame are usually determined by the shape and size of each piece.
To produce window mats with beveled edges, most people will have better results using a mat cutter with the cutting mechanism on a track. There are many models, starting at about $100. Handheld cutters require a great deal of skill and often result in a lot of wasted board. If a mat cutter is not available, the windows can be cut using a sharp mat (utility) knife and a heavy straightedge. Make the cut at 90°. A clean square cut is better than a sloppy 45° bevel. (You will also need a large self-healing cutting mat.) With practice, four-ply boards can be cut neatly by hand or with a mat cutter.
Thicker boards, double and triple mats, mats with multiple openings, and other configurations are generally too hard to cut in-house. Take several sheets of the mat board you are using to a framer and have those mats cut professionally. If your institution does not have a good mat cutter, you may wish to get a price for having all the mats cut; a framer can often do this for a small charge above the price of the board. Archival board is widely available; if in doubt, ask for a scrap and test the front, back, and edgewith a pH pen.
Some conservation suppliers offer a mat-cutting service. This is another very good option if a mat cutter is not available. The catalogs give measuring and order- ing information.
Mat board is made of layers; the grain of the layers alternates and the boards do not have very pronounced grain, but there is usually some difference in the two di- rections. When mounting and matting large items, try to determine the grain and have the longer side of the mat go with the grain. This will reduce the chance that the mat will cockle during the course of the exhibition. Some mat boards have a top (or front) layer of paper. The surface of this kind of board may look different depending on how it is held. Solid-core “museum”-type boards usually look much the same no matter how they are oriented.
Examine the art to be matted and determine how large the opening (the “window”) should be. If a print has a large white border, leave as much of it exposed as seems balanced. A tiny print can be matted very close to the image; a big print might look better with a half inch to an inch or more of border showing. The window can be centered on the board or the mat can be “weighted,”
that is, the bottom border can be somewhat wider than the other three. Some artworks look better centered;
others are more balanced to the eye if the mat is weighted. This is a matter of taste. There is no formula for how much wider the bottom border should be; it depends on the size and shape of the art and the mat.
Marking the Mat Blank
It is easier to cut mats from the backwhether using a mat cutter or by hand with a utility knife. All the marks are made in pencil on the back of the mat blank. Never use pens to mark the back of window mats. The marks should be erased after cutting to avoid transferring pencil marks to the art.
Find the midpoint of the top edge of the board by measuring it with a strip of paper. Fold the paper in half and make a dot on the back of the board, as shown in figure 6-5. Mark both the top and bottom. Mark the mid- points of the sides in the the same way (fig. 6-8).
M E A S U R I N G T O D E T E R M I N E T H E W I N D O W O P E N I N G One way to determine the size of the window is to cover the borders of the art with long pieces of mat board (figs.
6-6 and 6-7).
Fig. 6-7 Fig. 6-6 Fig. 6-5
SMALL EXHIBITIONS
To find the width (W) of the opening, position the pieces of mat board on the edges of the art (fig. 6-6) and move them until you get the desired effect. (Make sure they are parallel.)
Place a weight on each piece of mat board and measure the space between them with a strip of paper.
This is the width (W) of the opening. Fold the strip in half to find the midpoint.
Place the strip near the top edge of the mat blank, aligning its midpoint with the dot on the back of the board. Mark the width of the window on each side of the mat blank, both at the top and the bottom (fig. 6-5).
Determine the height (H) of the opening by placing the mat board strips at the top and bottom of the art (fig.
6-7). Measure with a strip of paper and transfer the (H) to the mat blank (fig. 6-8).
If the bottom of the window mat is going to be weighted, raise the midpoint mark a half inch or more, according to what seems pleasing. Mark both sides of the mat blank in the same way.
Draw lines connecting the marks, as shown in figure 6-9.
Normally, the mat should not cover any part of the image, signa- ture, plate marks, seals, etc. The mat can be used to hide flaws if necessary, such as mat burn (a discoloration caused by acid migration from previous framing materials), and it needs to cover enough of the art to hold it down firmly.
Cutting the Window with a Mat or Utility Knife
If cutting mats with a mat knife, follow the directions for marking the back of the board. Put the mat blank on a cutting surface. Place a heavy metal straightedge on the line to be cut. For good control (and to avoid injury), hold the straightedge veryfirmly or, preferably, clamp it to the edge of the counter. Cut with a heavy utility knife with a fresh blade, at a 90° angle. Make the cuts intersect about ⅛” (3 mm) so the corners will be neat. Turn the mat right side up and use a bone folder to smooth the edge as necessary.
Cutting Mats with Beveled Edges, Using a Mat Cutter Place a long piece of waste mat board on the bed of the mat cutter, for the blade to cut into, and shift it as it gets worn so there is always a fresh surface. This preserves the point of the blade. Once the point is dull or damaged, the neatness of the cuts will deteriorate rapidly. Always use blades made for your brand of cutter and keep a good supply on hand. Change blades as needed; the cuts will be neater and less effort will be needed to make them.
Figure 6-10 shows a basic mat cutter. The operator would stand at top right in this illustration.
Practice cutting scraps until you become familiar with the cutter and the process. The cutting is done on the pull stroke, that is, from top to bottom as you stand in front of the cutter. Since the blade is at a 45° angle with the point aimed to the left, most of the mat should be to the rightof the cutting head so that the bevel goes in the correct direction. (Trial and error will make this clear.) Mark the scraps with intersecting lines to simulate a real mat and practice beginning and ending ³⁄₁₆" (4–5 mm) beyond the intersections, as described below, in one motion. Stopping the cut midway usually results in a kink. Make sure the blade is cutting all the way through
Fig. 6-8
Fig. 6-9
Fig. 6-10 Logan Graphic Products, Inc.
SMALL EXHIBITIONS
the board and into the waste piece below. Control will come with practice.
Place a mat blank in the cutter following the direc- tions for your cutter. Move the cutting head along the track to the top of the mat. Press the point of the blade all the way through the board, about ³⁄₁₆" (4–5 mm) above an intersection, and right on a line. Pull the cutting head toward you in one motion, ending about 3/16" be- low the intersection of the lines at the bottom. Continue with the other cuts in the same way. The cuts must inter- sect at the corners so the bevels are cut all the way through and the middle falls out cleanly after the fourth cut.
Hinge the window mat to the backboard with pregummed cloth tape (fig. 6-11). One-inch tape is ade- quate for most mats. While the adhesive is still moist, close the mat and make sure the two boards are well aligned. Place a piece of polyester web in the fold and allow the mat to dry under a weight. A number of mats can be stacked to dry.
Pregummed tape is preferable to pressure-sensitive tape, which in time can ooze adhesive from the edges.
The water-activated tape also permits easier alignment of the two boards.