Step 7: Cutting the Matting

Matting Terminology

I’m going to describe how to do a double-mat. None of this is very complicated, and you should easily be able to adapt what I’m describing to single, or multiple matting jobs. The visual difference between a single mat and a double mat is huge. Double-matted works stand out as looking much more professional than just a single mat. I highly recommend you always use at least 2 mats. Don’t go overboard though. More is not always better. I’ve personally never used more than 3 mats.

In a double-matted work, the two mats are called the “back mat” and the “face mat.” As you may have guessed, the back mat is the matting that sits in back of the face mat. The back mat is the one that actually sits right on top of your artwork. The size of the window in the back mat is what will constrain how much of the artwork is actually visible.

Artistic convention suggests that you use a muted colour for the face mat, and a bolder colour for the back mat, since you’ll only see a small strip of it. The darker border of the back mat will serve to visually frame the artwork and separate it from the relatively muted colour of the face mat, of which much more will be visible. The face mat should be lighter than the colour of the frame itself, but this is really all totally subjective. You’ll settle on your own style and preferences.

The face mat sits on top of the back mat. This is the one that you see the most of after the framing is complete. In a double-matted job, you only see a narrow strip of the back matting, because you will cut the window in the face mat slightly bigger than the window in the back mat. The picture to the right shows the relationship between the two mats.

Matting terminology
Determining the Size

This step is just math. Don’t worry, it’s pretty easy math. To start off, take the measurements of your mounting board. In this example, the inside dimensions of our frame are 18″ x 15.5″. Recall that our rabbet is 1/2″ wide on either side, so that adds 1 inch to both dimensions, meaning that the mounting board should be 19″ x 16.5″. Mine is actually a little bit smaller, because I left a small gap to allow easy fitting. When you’re doing this step, use the actual measurements of your mounting board, rather than the “theoretical” dimensions, since the frame may not be 100% perfectly square (being off by even a millimeter affects squareness).

At this point, I usually switch over to metric, as doing these kind of calculations in imperial is just masochistic. For this project, my mounting board was 476 mm (about 18 3/4 “) by 413 mm (about 16 1/4 “). The diploma that I’m framing is 8.5 ” x 11 “, which is 216 mm x 279 mm, respectively. At this point, I should point out that you can’t just cut a window in your matting to this size, because you’ll see the edges of the artwork. You need to make the window just barely smaller than the artwork being framed, so you can’t see the edges. I’ll subtract 2 mm off each edge for this allowance, reducing my window dimensions from 216 mm x 279 mm to 212 mm x 275 mm.

So where does that leave us? The back matting (the one that controls how much of the artwork is visible) will be the same size as the mounting board (476 mm x 413 mm), and will have a window cut into the center of it that is 275 mm x 212 mm. This gives us a small (2 mm) lip all around the edge of the window to conceal the edge of the artwork.

Back matting dimensions
Cut the Matting to Size

Note: The matting materials themselves are archival-quality and acid-free. They’ll actually be in contact with the work being framed, so if you’re concerned about preservation of the artwork, you should use cotton gloves any time you handle the matting.

Take a sheet of matting that is the colour you want to use for the back matting and lay it face-down on a table. Mark the dimensions of the mounting board on the back of the matting, then use a strong pair of scissors to make a rough cut an inch or two outside these lines. I usually just take the mounting board, position it in a corner of the matting, and trace around it to make sure that my matting is exactly the same size as the mounting board.

Rough-cutting the matting
Place the matting in your mat cutter and line up the pencil line along the cutting line. Use the straight cutter to trim the excess matting away. Repeat this for the other edge, and you should be left with a piece of matting exactly the same size as the mounting board.

Do the same thing for the matting you plan to use for the face mat.

Calculate the Window Sizes

As we calculated in the diagram above, we want a window that is 275 mm x 212 mm, and the matting itself is 476 mm x 413 mm. To figure out where to make your lines, you need to calculate how much empty space will be on each edge of the window. First, I’ll do the width, then the height.

To calculate where to mark your lines in the x-axis, take the total width (476 mm), subtract the width of the window (275 mm) and divide by 2.

(476 – 275) / 2 = 100.5

This means the window will start 100.5 mm in from the edge. So measure horizontally and make a mark at 100.5 mm at the top and bottom of the matting (reminder: only make marks on the BACK of the matting). Connect the dots, and you have your first line. Extend the line all the way to the edge of the matting; don’t try to stop the lines right at the corners of your windows. You need the lines to extend well past the window so you can see them when you’re actually making the cuts (since the cutting tool will obscure part of your lines).
To make the line at the other edge of the window, you can either repeat this process on the other edge (measuring in 100.5 mm and making a mark at the top and bottom, then joining them), or you can add the width of your window (275 mm) to your existing line and make 2 more marks, continuing to measure from the same edge.
Do this same process for the top and bottom lines. Take the total height (413 mm), subtract the height of the window (212 mm), and divide the result by 2.

(413 – 212) / 2 = 100.5

Note that the result is exactly the same! 100.5 mm is the distance we went in when marking the left and right edges of the window. This is because we chose our measurements in the beginning such that the width of the matting surrounding the artwork would be constant (3.5 inches; go back to Step 1 to see, look at section “Decide on Sizing”).

The window in the face mat will be slighly bigger, so a little bit of the back mat will be visible. To determine the lines for the face mat, first decide how much “reveal” of the back mat you want. Typically, you’ll want between 1/8 to 1/4 of an inch of the back mat visible. Since we’re working in metric, I usually go with about a 4 mm reveal.

Take your measurements for the back mat and add 8 mm in each dimension (don’t forget, you’re adding a 4 mm reveal along each edge, for a total extra width of 8 mm in each dimension) and repeat the math I showed above.

Cut the Windows in the Mats

Follow the instructions for your mat cutting kit to cut the actual windows. For my kit, it involves placing the mat face-down on the bed of the kit, lining up the line with the edge of the guide. There is a bit of a trick here. Be mindful of which way your blade is angled. You want the bevel on the mat to bevel outward, toward the front of the frame. For my kit, that means I need to orient the mat such that the center is to the right of the line I’m cutting. Always make sure you put one or two scrap pieces of mounting board underneath whatever you’re cutting, to keep the cutting blade from cutting your actual guide.

This part is hard to describe, but easy to do in practice. Once you’ve lined up the window line with your guide, set the beveled cutter in the guide, line up the guideline with the start line for your window, and press down with your thumb to extend the blade and start the cut. Slide the cutter along the guide until the marker line on the cutter reaches the stop line for your window, then retract the blade to stop the cut.

Cutting the window out of the mat
Follow the instructions for your mat cutting kit to cut the actual windows. For my kit, it involves placing the mat face-down on the bed of the kit, lining up the line with the edge of the guide. There is a bit of a trick here. Be mindful of which way your blade is angled. You want the bevel on the mat to bevel outward, toward the front of the frame. For my kit, that means I need to orient the mat such that the center is to the right of the line I’m cutting.

Turn the mat 90 degrees and repeat this for the remaining 3 edges of your window. If you meticulously go just a hair past each stop line, then when you’re done, the middle should drop right out of the mat and you should be left with a beautifully crisp, sharp beveled window.

At this point, I usually attach the back and face mats to each other to ensure that throughout the rest of the process, the window openings remain lined up. I take two 1-inch strips of double-sided, acid free tape (I use Scotch brand, which I bought in an arts and crafts store [Wallack’s again]) and stick them to the back mat on either side of the window opening, about halfway between the window and the edge of the mat.

I remove the backing, exposing the second adhesive side of the tape, then I lightly set the face mat on top of the back mat, line up the windows perfectly, and press down on the face mat around where the tape is. Do this while wearing cotton gloves, or use some kind of acid-free protection while pressing on the face mat. Don’t press so hard as to leave an indentation on the face mat, but press enough so that the tape will hold.