Things You'll Need
Dexter mat cutter
Photograph or artwork
Matting your photographs or artwork is an excellent way to set them off visually and to protect them from sticking to the glass once framed. If you sell your work, people are much more likely to buy if it is already matted--all they have to do is buy frames to suit their tastes. A Dexter mat cutter is an inexpensive tool for cutting professional-looking mats. It works well as long as your volume of mat cutting isn't high.
Pick your mat board. White is the default color because it goes with anything, but you might want a color that complements your picture or the decor of the room where it will hang. If you are matting pictures to sell, use white, unless your customer makes a custom order.
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Decide what size frame you'll want. Unless you are doing custom work, pick a standard size since frames will be more easily found and are more affordable. Go up the next standard size from whatever size your picture is. For instance, a 5-by-7-inch picture would have an 8-by-10-inch mat. The hole in the center of the mat will be 5-by-7, and the 8-by-10 total mat will fit perfectly into an 8-by-10 frame. Other standard sizes include 11-by-14, 16-by-20 and 20-by-30.
Cut the mat board to the size you need. Mat board comes in sizes much larger than you'll need, so use your Dexter mat cutter to cut out an 8-by-10 mat. Simply measure off 8 inches one way and 10 inches the other. The mat cutter's blade adjusts angles, so turn the knob to 90 degrees to cut straight edges.
Draw off a place to cut the hole. You can center it or leave more space on the bottom. Centering is the most popular method. Leaving extra space at the top or on either side doesn't look good. To center the hole, take the width of the picture and subtract 1/4 inch. (This allows a hole slightly smaller than the picture so the edges of the picture don't accidentally show.) Now take the width of the mat and subtract measurement you came up with in the previous sentence. (Example: If you are putting a 5-by-7 picture into an 8-by-10 mat and the picture is vertical, subtract 1/4 inch from 5 inches, leaving 4 3/4 inches. Now subtract 4 3/4 from 8, leaving 3 1/4 inches.)
Divide by 2. (In the example you get 1 5/8 inches.) On the back--not the front--of the mat, measure that distance from one side in two places and make a mark. Use a straightedge to draw a line between the two marks all the way across the mat. Do the same on the other side.
Use the same formula to figure the distance from the top and bottom. (In this example, subtract 1/4 from 7 to get 6 3/4. 10 minus 6 3/4 equals 2 1/4. Divide that by 2 for 1 1/8 and make your lines 1 1/8 inches from the top and bottom.
Cut the hole. Change the blade setting to 45 degrees to get a beveled cut. Place a scrap piece of mat board underneath; otherwise, the front side of board will have a ragged appearance, and you may cut the table or floor beneath your mat. The four lines you drew will have formed the outline for your hole. Place the Dexter mat cutter 1/4 inch before the spot you want to start cutting. (The inside hole will be smaller because of the angle of the blade, so you'll need to cut a little past your markings so the center will fall out cleanly once you've cut all four sides.)
Place the cutter against a T-square or other straightedge to ensure a straight cut. Hold the straightedge and the mat perfectly still. You may need to put the mat on the floor and hold it in place with your knee, or get someone else to hold the mat. Push the blade down the line until you get 1/4 inch past the cross marking. Repeat this step for the other three sides.
The cut should fall out by itself. If you didn't go 1/4 inch over on any of the cuts, you might need to twist it a bit, then use a blade to clean up the ragged corner.
Tape your picture into the hole. Tape only the top and allow the picture to hang freely. If your picture isn't perfectly aligned, fix it and re-tape. If desired, put it in a frame. If you are selling your work, you can leave frame choice to the buyer.
If you plan to do a larger volume of work, invest in a table top mat cutter which holds your mat in place and provides its own straightedge.
Use acid-free tape to to hold picture in place. Otherwise, you're picture will be ruined over time.
Always be careful using sharp blades, and keep them stored away from children and pets.