Next time you are in a gallery, restaurant, or shop, take a look at various matting jobs and compare reveal sizes, colors, and borders. Do they compliment the work? Are they overbearing? Was your eye drawn into the work or out to the mat and frame arrangement?
While they are often twice the price, double mats can add considerable impact to your artwork. There are a number of things to consider when looking at using double vs. single mats:
Colors
You are dealing with two colors, so having them not only compliment each other but your artwork and frame can be a complicated step. Often when arranging double mats, you will want to match the inner (or bottom) mat to a dominant color in your picture. A neutral color can then be used on top. This draws the viewer into the actual piece rather than being distracted by dominant colors on the outside.
Reveals
Next are the effects of the reveal. A reveal is the amount of your bottom mat showing around the opening. Sometimes this is referred to as the mat offset. Standard double mat reveals are usually 1/4" or 3/16"; however, the size of your piece and the look you are going for will change this considerably. I've seen reveals as small as 1/8" to as large as 1/2" work quite well on small and large pieces respectively. Certain combinations, such as white on white, can be very effective using larger reveals.
Bevels
You will also want to consider is the impact of the bevel — the angled cut around the opening of your mat. You can choose to make the bevel a feature of your mat or have it blend in and go undetected. Use a bright white bevel with two black or dark-colored mats to give a v-groove like border while retaining the depth of two mats (and less the cost of an actual v-groove). Similarly, you can do the reverse with a black bevel and white mats. Bevels on conservation mats are normally a stark white, whereas on standard acid-free mats they can be a cream or off-white color.
A less commonly used bevel is the reverse bevel. This is where the bevel is cut on the bottom of the mat, thus hiding it away from the viewer. The advantage of this is two-fold: the bevel does not distract from the matting, and it provides an extra space between top and bottom layer, creating a unique effect. For the cost-conscious, reverse bevels and other 'extras' can add cost to the mat depending on the framer or source.
Experiment!
The most important thing, however, is to experiment. With the advent of speedy Internet and digital photography, a novice can easily try out combinations of mats and frames from the comfort of their own home with tools like MatShop's MAToMATic or others. The last thing you want is an inspired piece uninspiringly framed and matted! At the same time it's easy to go overboard. Use your custom framer for advice — they're extremely knowledgeable and will usually have a selection of mat samples on hand to test.
As you weigh the options and make decisions about your next matting job, you'll notice that you spend a lot more time standing in friends' homes taking note of their matting jobs then the actual piece of art! After all, framing and matting can be considered an art form itself.