Picture Framing & Art Conservation

Information, advice, and inside tips from a professional picture framer and artist.

©2000-2007 Sharon Hudson

In addition to being an artist, I was a picture framer for over 20 years, so I know that many people are frightened at the prospect of framing a work of art.  They need help!  Framing prices seem high, and most people know nothing about the process, so they are insecure.  Luckily, the do-it-yourself picture framing movement has demystified framing somewhat, and I hope this article will also provide enough information on framing and conservation of fine art to help you get started on framing your pictures.  And your framer should be willing and able to explain what is going into your picture frame job, and why.

One of the major purposes of framing is to diminish or delay the effects of aging on artwork.  This means protecting the art from damage arising from (1) physical abuse like bumps, punctures, abrasion, and dirt, (2) the chemical effects of air pollution, (3) excessive light, (4) excessive heat or cold, (5) excessive humidity or dryness, and (6) insects.

Young artists generally pay little attention to the quality of materials and the future of their work, but as we get older we try to ensure that we use "artist quality" materials in our work.  These are materials such as pigments and papers that will not deteriorate over time.  Nonetheless very few artists succeed in using these materials all the time; most don't have enough money to do so, and many contemporary artists work spontaneously in unconventional media, grabbing anything at hand and including it in their work.  In addition, I have found that not all materials labelled "artist grade" are in fact lightfast (nonfading).  Therefore people who buy original works of art should not assume that the work is going to last "forever" (why should it? nothing else does), but should instead consult with the artist and framer, and use common sense in considering the materials used and how to best preserve them for a reasonable cost.

Framing to fully preserve the art is often called "museum" framing, but museums must preserve art for all time, while most of us need to preserve it only for a lifetime or two.  Museum framing has a very stringent sent of protocols that demands, among other things, the full reversibility of anything done to the art.  The framing discussed here might better be called "preservation" or "acid-free" or "acid-reducing" framing, which is similar but less stringent, and allows for some irreversible procedures, such as mounting with non-resoluble adhesives.  I will also focus on works on paper, since the vast majority of my own work is on paper. 

Preservation framing has become increasingly important because of the increasing acidity of papers and pollution of the atmosphere.  Most papers are made from wood fibers and are more or less acidic, and, upon exposure to ultraviolet light and acids in the air or acids in objects placed near them, become even more acidic and turn brown and brittle.  The "cheaper" the paper, the quicker this happens; everyone knows a newspaper turns yellow and brittle very quickly.  At the other end of the spectrum are "acid-free" paper products, either made of non-wood plant fibers like cotton or linen (hence called "rag") or of alkali-buffered wood pulp.  Using these products in producing, framing, and storing art will preserve the art for the longest possible time.

The framer can help primarily by surrounding the artwork -- front, back, and sides -- with acid-free materials.  One purpose of the mat, for example, is to provide a three-inch buffer between the art and pollutants that creep in from the edges.  Of course the mat itself should be acid-free.  When acidic mats are put in contact with the art paper, acid migrates from the mat and creates visible browning of the art paper, not just directly under the mat but also creeping into the art from the edge of the mat.  This may be noticeable around the edge of the mat widow within a year or so, and damages the fresh, pristine look of the art.

Of course, the art paper should also not come into contact with acidic materials from behind; never put corrugated or grey cardboard up against the back of a valuable work of art.  Foam boards are not usually completely acid free, but they are quite inert and, except for the most valuable or delicate pieces, are probably adequate for backings.  But don't mount valuable art onto foam board; it is too easily dented and punctured. 

Frequently compromises are made (not by museums, but by the rest of us).  For example, less expensive, acidic materials may be used inside the frame, but not right next to the art.  This is okay, if done correctly, and may prevent visible damage for many years, but keep in mind that it is the acidity of the entire environment within the frame that will ultimately affect both the art paper and media.

If you want to preserve works on paper for many decades, then, you should use acid-free mats and backings.  But this is expensive, so be reasonable.  If you have a poster, or a crayon drawing with fugitive colors that will fade in a year, there's no point in trying to make the paper last a century.  The good news is that the life span of even very acidic paper can be greatly lengthened by acid-free framing, especially by mounting it to acid-free backing, because then the acids actually migrate OUT of the paper, although the paper will still gradually darken.  If you don't mind the gradual darkening, even works on newsprint will last just fine if properly cared for.

The mat also creates room for the art paper to expand and contract with temperature and humidity changes.  This is very important.  If the paper butts up against the frame, or is constrained around the edges in some other way, the art will wrinkle when it expands.  We have all seen this, usually on posters, and it's not a pretty sight.  The thinner the paper, the bigger this problem.  Expansion is the main reason that artworks on paper must hang freely in the mat, hinged only in a couple of places at the top.  But, if you do not want to use a mat, there are a few other ways to prevent wrinkling (as well as to separate the glass from the artwork), which your framer can explain.

The other consideration in the hinging is that the hinges should be weaker than the art paper if the art paper is at all fragile.  This is so that the hinges and not the artwork will tear if the frame takes a serious bump.  But the inexorable pull of gravity wears on the fibers of the hinge and the paper even without traumatic events. If you have an older work whose hinges have failed, therefore, don't be too critical of the framer.  Even modern adhesives may not be able to perfectly straddle the line between permitting the hinge to fail when necessary, but to otherwise hold perfectly over decades, especially if the artwork is moved around.

If a work of art is not flat, or is structurally fragile, you may want to mount it, perhaps with the artist's permission.  However, anything that changes the original intended state of a work of art generally decreases its market value, so very expensive or historical works of art are only mounted in the most unusual circumstances, and in consultation with a conservator.  Whether or not to mount a work of art is always a trade-off between your enjoyment of the work in a flatter or more regular state, and its eventual resale value, if significant.

If you value the work of art that you mount, always use "museum" mounting or wet mounting; never use spray, rubber-cement type adhesive on valuable works, as it starts to dismount and bubble within only a few years.  Wet mounting is done with a water-based adhesive, these days often in a vacuum press.  It is must be done by an expert.  If you plan to mount a work of original art, be sure to take it to a frame shop with experienced personnel working in a clean, roomy, organized, and non-distracting environment.  Mounting is a stand-alone process, and you don't have to have your mounting done at the same place you buy your frame.

In my opinion, mounting is the most difficult and risky framing activity; many things can go wrong and most are irreversible.  Which is one reason not to mount unnecessarily.  On the other hand, I prefer my own art to be flat and would always mount it if necessary to make it that way, and hope that people who buy my work will do so as well.  If possible, I would always mount works done on newsprint, because thin papers wrinkle more in the frame, and because mounting newsprint to acid-free backing is chemically good for it.  Mounting any thin paper is difficult, though, and once again, experience is the key: you don't want your framer to learn anything new and interesting about mounting using your original art.

The third important function of the mat is to separate the glass from the surface of the artwork.  Placing glass tightly against almost any media is damaging over time; for example, if you place glass directly against either oil or acrylic paint or oil pastel for any length of time, the paint can stick to the media and either discolor it or pull it off. The air space created by the mat also protects the art from moisture, heat, and cold.  Moisture, which occurs not only in the form of atmospheric humidity but also sometimes as condensation behind the glass, is damaging not only for the obvious reason (water drooling on your art is not a good thing), but also because mold and mildew may grow.  Dry pastels and charcoal drawings should have a deeper air space, because an electrostatic charge may cause the chalk particles adhere to the glass surface if it is too close.  For the same reason, plexiglass should not be used to glaze these media.

Like papers, most media are also subject to environmental damage, though this damage may be slower and less visible.  The yellowing of varnishes and other coatings is one example; I think it is a good idea to use as few of them as possible.  The historical trade-off here is that varnish has traditionally been used to protect the painting, because the varnish--and the dirt it contains--is removable.  But it is the varnish that cracks and darkens, discoloring within only a few decades, and over centuries almost completely masking, the bright colors of the original painting.  Naturally one should use a kind of varnish that is removable and does not crack or yellow, but there is no perfect varnish.  Removing old or dirty varnish is not a do-it-yourself project.

Sometimes "varnish" or some kind of coating--usually acrylic-based--is used on works on paper to regularize the glossiness or texture of the surface. But for protective purposes alone, there is no reason to varnish a work on paper because works on paper will be protected by glass anyway.

The media damage most of us are concerned about is pigment fading; obviously, we do not want any of the major colors to fade noticeably.  Artists should do their utmost to use lightfast materials, but this doesn't mean we are limited to traditional media, since many other materials either happen to be lightfast or are designed to be so, such as many wallpapers and exterior paints.  Artists and framers should be especially suspicious of magazine images used in collages; they are almost never lightfast, although some colors may last a lot longer than others.  My experience is that both photographic printing and photocopying technology have improved so quickly during the past decade that many of these reproductions are now (or soon will be) about as lightfast as many artists' materials, thus removing the main impediment to collage as a fine art form.  Buyers should consult with artists and take precautionary measures, such as framing with UV-protective glazing, if some materials are in doubt.

Strong light, especially ultraviolet light, hastens the damage to acidic papers and causes fading of fugitive pigments.  Flourescent light and sunlight are much more destructive than incandescent light, so avoid hanging art near flourescent light or in direct sun.  Unfortunately, regular picture glass only filters out about half of the sun's UV rays.  If there is reason to be concerned about fugitive pigments, you can glaze with ultraviolet-absorbing glass, which is available at your framer for about 1-1/2 times the price of regular glass, or with UV-absorbing plexiglass.  Both absorb over 97% of UV rays and are often used by museums.

Sometimes the media themselves emit chemicals that are damaging to each other and to the paper.  For example, artists are not supposed to paint with oil paint on paper, although many do so, including me.  It obviously embrittles the paper over time, but I think you can just mount the artwork to provide structural strength, and not worry about it.  Oil-based media also emit fumes that gradually deposit an oily film on the inside of the glass.  This probably doesn't damage anything much, but if it becomes noticeable you might have to open up the frame and clean the inside of the glass.  I was shocked to see such a film develop after only a few hours once, when I was unable to protect an oil pastel from the sun during an outdoor show!  During the same show, moisture also condensed and ran down the inside of the glass on another piece, but did not damage the art because it was properly separated from the glass.  The lesson: most art is not meant to be outdoors.  By the way, NEVER leave your framed art in a hot car, where condensation can be rapid.

Paintings on stretched canvas are traditionally not framed behind glass.  However, you may wish to do so if you live in a particularly dirty area.  Remember, one of the main reasons for glazing is simply to protect the art from regular old dust, dirt, and oily smog, which will adhere to the surface of your paintings just as it does to everything else in your house.  Although it is true that oil paintings should be allowed to "breathe" (because oil paint continues to emit vapors for many decades while drying) and should not be tightly enclosed, in a dirty urban environment, one may nonetheless choose to protect the front of the painting by glazing while hoping that it may breathe somewhat through a ventilated back. However, the glass will probably have to be cleaned from the inside occasionally to remove the oily film, and I would not recommend glazing an oil painting that is less than several years old.

When framing works on paper and sometimes works on canvas, wood frames are backed with tight paper backings.  This keeps out dirt and insects.  It is easy to puncture these backings, but they are easily replaced.  Try to patch any holes that occur.  Metal frames are not backed, mostly because there is no very aesthetic way of doing so.  This means that insects like silverfish can creep in around the edges; it's rare, but it happens.  Luckily it is fairly easy to open up a metal frame and clean things up.

Finally, use some judgment about what you do with both your unframed and framed art once you get it home.  All unprotected paper and textile items are gradually damaged by smoke, chemicals, and oils emitted by cigarettes, incense, candles, etc.  No original work of art on paper or fabric belongs in the bathroom; put ceramics, glass, wood, or non-corroding metals in that humid environment.  Don't put any unglazed work in the kitchen or it will soon be covered with oil.  Nothing valuable belongs over the stove, and watch what you put over your heater.  No original art should be placed in direct sun, and nothing very heavy or sharp belongs over the head of your bed.  Use picture hooks rather than nails to hang your art. You can keep pictures straight by placing a little reusable sticky putty behind a lower corner; this removable putty is sold in hardware stores for sticking posters to the wall.  As for sculpture, if you live in earthquake country, be sure to fasten breakables to the shelves with florist's putty, and fasten the shelves to the wall.

Storage is not quite as simple as it seems.  Store works on paper between acid-free papers, and not enclosed with works in oil-based media.  Never store art in the garage because car exhaust is especially damaging to art; if you absolutely must do so, seal it in plastic.  Pastel and charcoal drawings obviously must not have things slid across their surfaces; they require a cover sheet held firmly in place.  If you have to roll an acrylic or oil painting, roll it as loosely as possible, around a tube (to avoid accidental crushing), but separated from any cardboard, with the painted side out, which results in less cracking.  Some insects are art connoisseurs and can be a problem; you'd be surprised at the ability of silverfish, moths, and other insects to get inside your seemingly tight frames!  Mostly they just wiggle under the glass and ruin your mat, but they can do more serious damage.  For this reason, try to repair any holes in your paper backings.  Although enclosing art for long periods in airtight containers isn't the best, if you really have to store an artwork for a long time, even a framed one, you may need to enclose it in insect-proof plastic sealed with tape.  It pays to check on the condition of your stored art every so often.

Well, by now you are probably afraid to even touch a work of art, to say nothing of own one!  But the good news is that the vast majority of all art is framed rather conventionally without much fuss, and then hung on a wall, managing to stay there, out of trouble and looking fine, with no further upkeep, for many years.  The owner, on the other hand, gradually shrinks or expands (or both), wrinkles, darkens or fades, and requires continuous protection from the elements and expensive maintenance.  (Well, okay, maybe that's not exactly the GOOD news...)

For more information on protecting your artwork, look at the following site, which provides brief, thorough, and readable information on the preservation of many kinds of artifacts.

Along with conservation, enhancing the work of art through tasteful frame design is the other major purpose of framing.  You should go to an experienced, professional framer to get help with your frame design.  Remember, you can get design help at a frame shop without committing to a purchase, and in shopping around for a frame you should review several design options as well as different price alternatives.  Different shops have different mouldings, design ideas, and specialties (fabric or French mats, for example).  Don't be shy about utilizing professional expertise.  And, to avoid basing a lifelong design decision on small differences in price, why not start by mentally "budgeting" a generous amount for the frame that is sure to cover almost any design choice?  Then you can stop worrying about money and have fun with your design.

In addition, be flexible when considering design options.  I am an experienced designer, but I find it useless to "armchair design" a frame; I am always surprised by what happens when I see the actual colors and textures of the mats and frames next to the artwork.  And don't bring too many preconceived notions with you.  Here are a few common ideas about framing design to leave behind:

1.  I am going to use an inexpensive readymade frame, or even a frame I already have around the house .  .  .

Believe me, for any picture bigger than a snapshot, your chance of achieving a good frame design with a frame you already own is nil.  And although the choice of tasteful readymade frames is better than ever before, the chance of finding a readymade frame that is the right size, proportion, and style is ALMOST nil, except in the case of a few standard-sized canvases.  Suffice it to say that frames designed to look adequate on many things look truly excellent on few things.  And you also don't want to be designing to coordinate with or fit the frame instead of the art.

2.  It's ridiculous to spend more on the frame than I spent on the art .  .  .

Ironic, yes; ridiculous, no.  Because the price of the art has nothing to do with it.  What you are spending money for is to create an object that will provide you with pleasure for some period of time.  You will add both real and aesthetic value to the art and increase its lifespan through better framing, and diminish all through bad framing.  In fact, for small or inexpensive works of art that are valuable TO YOU, you will probably spend much more on the frame than on the art.  And it's not a good idea to skimp on something you will be looking at for many years.  As someone once said, "I never look around my house and remember or regret how much money I spent on something, but I often regret spending too little on something."

3.  I have to use a mat and frame that match my decor .  .  .

Only slightly true.  The first consideration is to make the frame complement the art.  Only then, within the range of GOOD design possibilities, choose the one that fits best with your lifestyle (you might want to bring color samples for your walls, upholstery, etc.).  But don't frame your picture in dark wood just because the rest of your furniture is dark wood.  And ALWAYS choose the mat color from the few choices that best complement the artwork. 

4.  "Traditional" art has to go in traditional wood frames, and "contemporary" art has to go in very simple wood or metal frames .  .  .

Not necessarily.  The design or complexity of the frame should relate to the design or complexity of the piece as much as to whether it is "modern" or "traditional," and there is a far greater variety in metal frames than there used to be.  Both traditional and contemporary art may be simple or complex, and you may be able to achieve your desired "look" in either wood or metal.

5.  "More is better" (multiple mats, etc.), or "less is better" (simple white mats, etc.) .  .  .

Neither is better.  What is better is what complements the art.  Decorative framing can be fun, and may well be the best choice for strong decorative art. But unless it is done very well, it detracts attention from the art, and is therefore often used to "dress up" empty or bad art in the decorator market.  Perhaps in reaction to this, many people think that original works on paper look "best" (i.e.  most serious) in plain white mats, like you see in museums.  But this is equally bad: white mats do not complement most works of art, unless the work shows a lot of white paper or at least a white border, and even then it may not be the best.  Good framing can range from elaborate to austere, but you must differentiate between, and eventually balance, "the look" you want and what is visually most complementary to the art.

6.  I want my frame to be dramatic and memorable .  .  .

Wrong: you want your ART to be memorable.  The last thing you want is an "eye-catching" frame that detracts from instead of supports the art.  I once went to a museum exhibit of early 20th-century California Impressionism.  The paintings were forgettable under a century of dirt and yellow varnish, but I will never forget their stunning, hand-carved, wooden art nouveau frames.  Unfortunately nobody is in danger of finding such magnificent frames today, but be sure your framing is the supporting actor, not the star.  This does not mean the mat and frame cannot be decorative and interesting.  Just remember that the successful frame job is the one where people either remember your art looking its best, and not the frame, or the art-and-frame combination as an integrated and inseparable whole.

So how do you go about achieving this harmonious and integrated look, especially given the huge array of options available? That's where expert design help is necessary, but I hope the information below will also be valuable.

I will focus on works on paper, because most of my own work is on paper.  Original art on paper is almost always matted, and, visually speaking, the mat is much more important than the frame.  The 80:20 rule applies here: The mat (color, texture, proportion, etc.) will provide about 80% of the final effect, and the frame about 20%.  So focus most of your attention on the mat.

The first thing I think about in matting is color, not specific colors but rather in terms of warm and cool.  Does this work lend itself to warm tones (reds, oranges, yellows, beiges, browns, warm neutrals) or cool tones (blues, greens, purples, greys, cool neutrals)? Frequently there is one obvious choice, but equally often the piece can be successfully moved in either direction.  Even if your mat choice will ultimately be some tone of grey, white, or off-white, there are warm and cool versions of each of these options.  If there are good options on both the warm and cool sides, you can eventually make your choice on the basis of your personal preference, your decor, or what type of frame you want to use.  But don't narrow the mat color down too much until later, after you have looked at the frame options.

The next things to consider in mat color are saturation and value.  "Saturation" is how intense or vivid or dull the hue is.  Lime green and fire-engine red are both very saturated colors; grey is completely unsaturated.  "Value" is the brightness, or the lightness or darkness, of the color.  Black and white are the two extremes of value.

There are three basic visual principles to keep in mind: the eye is attracted (1) to saturated colors; (2) to high-value (light) colors; and (3) to high-contrast edges, especially sharp corners.  And remember: Everything is relative; the eye also tends to be attracted to whatever is different from its surroundings.

You want your viewer's eye to be attracted primarily to the art (or the center of interest within the art), NOT to the mat, the frame, or (usually) to the edge between the mat and the art.  So what does this mean?

It means first that the mat should be less saturated or vivid than the art.  This is why almost all mats are relatively dull or neutral colors.

Second, the mat should usually be lighter, but not too much lighter, than the art.  Mats are usually somewhat lighter than the art because people's walls are usually white or very light in color.  Making the mat lighter than the art eases or softens the transition between the art and the wall, and focuses attention on the art by making the contrast between the art and the mat slightly greater than between the mat and the wall.  A light mat also visually gives the art room to "breathe" or expand, while a mat darker than the art visually constrains and shrinks the art.  Rarely is the latter effect desired. Finally, a black mat might look good on the framer's table, but it usually looks disastrous on a light wall.

The apparent contrast between the edge of the art and the mat should not be greater than the contrast within the art, or at least in the center of interest of the art.  If the value or color of the mat differs too much from the value or color of the edges of the art next to it, the viewer's eye will be attracted to that edge, which is rarely desired.  Minimize this contrast to keep the viewer focused IN the art and not too much on its edge.

In spite of this general principle, it is common to "outline" the art with a dark second mat or other decorative edging (painted bevel, filet, etc.).  This is done for decorative effect, to add depth, to "pick up" a color in the art, to help relate the frame to the art, or to slightly emphasize the edge of the art.  Ask yourself if indeed you want to draw any attention to the edge of the art (which, by the way, also encloses the art).  Sometimes you will, sometimes you won't; this depends on your interpretation of the composition.  Extra edging may also be undesirable if there are many lines near the edge of the art.

If you do choose to outline your art, do so subtly.  The prominence of the edge you create will depend both on its color and its amount; that is, narrow edgings are less visually obtrusive than wider ones.  A 1/16" black edge might be the visual equivalent of a 1/8" dark grey edge or a 1/4" light grey edge.  So there is a lot of flexibility here.  But be wary of any edging that appears, from normal viewing distance, more contrasty or prominent than the art itself.

Remember too that the bevel of the mat, which shows the edge of the matboard, will be near-white and may play an undesired role in your design.  (The bevel is usually not visible in the corner samples used for designing, so it is easy to forget about this until it is too late).  Also keep in mind that if your mat is not acid-free, this nice white edge will turn yellow in a few years.  Your framer will give you options for eliminating unwanted bevels. 

Putting all these optical factors together, you get what is basically the norm for tasteful everyday matting: a light, neutral mat, perhaps with a subtle interior edging (double mat).  And, as you can see, unless your art includes a lot of white, or has a white edge such as in a traditional etching or lithograph, a white mat is not usually indicated on a purely visual basis.  (In this article, the term "white mat" refers not only to pure white, but all the off-whites, which are much more commonly used).  However, white can certainly be the most complementary choice for some pieces, including some very light, delicate works, and strong works with no dominant color direction and/or a variety of colors around the edge.  In these cases, white is more or less the default color.  Likewise, a dramatic black mat, which draws attention to the edge between the mat and the light wall, is appropriate only in the rarest cases; even then, the edge between the mat and the wall should probably be softened by a substantial frame of medium value.  Finally, for a very "rich" artwork, including many fabric or textured works, you may find that all standard paper mats somehow look weak or anemic.  In this case, try one of the many available decorative paper mats or a fabric-covered mat.  Most custom frame shops will have a selection of fabric mats available, and some will cover mats with fabric you provide.

You may note that some of the frame designs that I have presented as less desirable are the ones that are most striking at first glance.  This is because your eye is attracted to a high-contrast object.  This is the kind of presentation that will make something stand out at first glance in any cluttered environment--in other words, how someone might design a poster to "sell" in a poster shop.  However, what most people want in their home environment is a presentation that is more restful, and allows them to focus on the most interesting parts of the artwork without distraction.  This is more respectful to both you and the artwork.

Finally, how wide should you make your mat? This is where your framer will come in handy; deviations from the "standard" (about 3") will be based on his/her experience.  Too narrow, and the job will look cheap and skimpy; too wide, and the art will seem overwhelmed.  Finally, be sure that the apparent width of the mat and the frame are not too similar; this always looks bad and attracts the eye to the repetition of similar forms (the ladder effect).  The norm is for a wider mat and narrower frame, as shown in the center below, but a wide frame with a narrow liner or inner edge is also fine in the right circumstances, and common with works on canvas.

It is very important that the bottom of the mat be about 20% wider than the top and sides, which should be equal.  This is standard, and don't let anybody talk you out of it!  Optically, this proportion results in a visual balance in which all four sides look equal.  If you in fact make all sides equal, the mat will look uncomfortably narrow on the bottom to most people.  There are a few exceptions to this bottom-bigger rule: a very narrow mat that is just functioning as a visual extension of the frame; an extremely wide mat, as used with miniatures, in which case the bottom is sometimes much larger than the top or sides; and some ethnic art, where other cultural aesthetic norms apply.  And, if you are committing the unpardonable sin of trying to fit an artwork into an existing frame that does not permit the extra width at the bottom, I think it is better to shave a little off the top of the mat to add to the bottom than to make all sides equal.

When you have narrowed down your mat choices to a handful (perhaps a few warms, a few cools, a few neutrals), it's time to look at the frame (or moulding) options.  You won't be able to make a final mat decision until you have coordinated it with the frame.  You will want to look at cool frames to go with cool mat options and warm frames to go with warm mat options.  Avoid switching tones: for example, using a gold or warm wood frame with a blue mat.

You essentially have three choices in picture frames: wood finish frames, gold or silver finish (wood) frames, and metal frames.  Most but not all wood finish frames are warm in tone, and look best with warm-toned mats.  As for metallic finished wood frames, while obviously gold frames are warm and silver frames cooler, there is in fact a huge variation in both.  There are both warm and cool silvers and golds, and all may have a red (warm) or green (cool) undertone, which must be respected when coordinated with the art and the mat colors.  Metal frames also come in many metallic tones and textures, as well as many nonmetallic colors, and many styles, and are generally chosen for color or simplicity.  In addition, metal picture frames are structurally stronger than wood ones, so you can use a much thinner frame, for a more minimal frame look, with a metal frame than you can with wood.

When choosing the frame, avoid choices that are dominating or too high-contrast relative to either the mat or the wall.  You do not want your frame to be "eye-catching." However, there is some flexibility here, since the frame is expected to be more prominent than the matting, though still secondary to the art.  Choose a frame that is not, visually, too "light" or too "heavy" for the matted work; again, a wide mid-toned frame may have the visual weight of a thin black one.  Interestingly, a textured or decorative moulding breaks up the surface and softens the visual impact of a frame, so a "decorative" frame could easily be less visually dominating than a plain one.  Likewise, the reflections of a shiny surface also break up the light and "lighten" a dark frame as well as make it more dynamic; for this reason a shiny black metal frame is often a better choice than a matte black frame. Suggestion: Avoid heavy black frames placed against white walls!

After physical strength, tone, color, and visual weight of the frame, think about the finer points of style and decoration of the moulding.  Choose a moulding style that complements the art, as well as the mat if there is any textural or decorative element to the matting.  As you narrow down the frame choices you will simultaneously narrow down the mat possibilities, finally concluding with the right color and value of mat to both complement the art and coordinate with the frame.

The same design principles apply to works on canvas as to works on paper, but stylistic conventions are different and some options are more limited.  Stretched canvases are usually not matted with paper mats, but often they are separated from their frames and given visual breathing room with a fabric-covered wooden liner.  These liners come in very limited colors (usually white or off-white, unless you have one especially built or altered), and are always of equal width on all sides.  You just have to work within these limitations, although you can paint your liner if you want.

On the other hand, especially with contemporary stretched canvases, a very minimal framing look is also common.  So you can choose a rather thin frame profile as long as it is deep enough to cover the stretcher bars.  You don't have to be concerned about strength because the canvas can always be hung by the stretcher bars instead of by the frame.  You can even leave the piece unframed, if the edges are reasonably attractive, or go to the hardware store and buy some simple wood stripping and nail it to the edges of the stretchers.

Within the limits of the visual principles I have outlined, don't be afraid to do something interesting, textural, original, or even whimsical with your mat and frame design if it suits the piece.  I am far from a purist in framing, and I believe that the art and frame together constitute the finished art object.  But if you choose decorative framing, just be sure the framing does not visually detract from the art it serves.  Likewise, however, a frame that is too plain or insufficient is equally diminishing to the art.  Don't underestimate the power of a good framing job to "improve" a work of art.

Finally, if you remember only two things from all the preceding information, let it be these: First, take advantage of and be willing to follow professional design advice--although by "professional" I don't mean someone who has worked as a framer for two months as a summer job.  And second, keep the primary focus on the artwork--not on the mat, the frame, or your decor.

While you are shopping around for moulding and design options, be sure to compare prices, too.  There is a substantial difference between a 400% markup and a 600% markup, and there will be even greater price differences in special services such as mounting, fabric mats, oversize framing, building shadow-boxes, etc.  You can get a pretty good price comparison by choosing a moderate size, say 30"x 36", and asking several shops for the individual prices of the following items in that size: (1) regular picture framing glass, (2) a single acid-free mat without backing, (3) a wet mount on acid-free board, and (4) the fitting charge for either a wood or metal frame (they will probably be different).  Items (1) and (2) will reveal their standard markup, and (3) and (4) may tell you something about how they might price their labor if you require some kind of special service.  Remember, if you actually need your art mounted, it can be done separately at the least expensive competent shop.

A major factor in the price of your frame, of course, is size.  But for the same size piece, a work on stretched canvas will almost always be cheaper to frame than a work on paper because there is no glass and matting to buy, though you may have to buy a liner.  In any case, the price simply increases gradually with size.

The same is not true for works that are matted and framed under glass.  Here the price increases incrementally until the glass and mat size reaches 32"x 40".  At that point, prices rise dramatically, mostly because you have entered the realm of "oversize" mats, which are not only very expensive but are also limited in color.  (For this reason, whenever aesthetically possible, I try to keep the artwork I create under a final [matted] size of 32"x 40".) The next breaking point is 36"x 48", above which you will have to glaze with plexiglass, which is quite expensive.

If you are on a budget, one way to divide your framing bill into two approximately equal parts is to frame your art in two stages.  Design the entire job at one time, but purchase the frame later (make sure that frame or similar frames will continue to be available).  First, mat the art and put it into "clips and glass," a system of plastic brackets that hold the glass, mat, art, and backing "sandwich" together without a frame.  Clips are inexpensive, unobtrusive, and a fine way to present the work until such time as you can afford to add the frame.  At a later date, you can buy the frame, and the premium you will pay for the two-stage process is only a relatively small charge for the clips and their assembly.  The clips are reusable. 

This option has a few practical limitations: First, clips and glass shouldn't be used with pieces larger than 32"x 40"--and that's pushing the envelope a bit.  Second, if you live in an urban environment, try to frame the piece within about a year, because by this time the mat will start to discolor slightly around the edges where polluted air enters between the glass and the mat.  By the same token, if you smoke in your house, this is probably not a good option.  Third, you must use care when handling large pieces in clips and glass, although I have framed and transported many large clipped pieces and never had any problem.  And finally, the edge of the glass will be exposed, which may not be compatible with rambunctious children, and I wouldn't hang a picture in clips and glass over the head of my bed, especially in earthquake country.

A few words about glass: The vast majority of all glazed pictures are glazed with regular picture-framing glass (which is like window glass, but thinner), but there are other options, all of which are more expensive.

There are several kinds of "nonglare" glass.  The cheapest and most common is a slightly frosted glass.  I almost never recommend this.  First, it doesn't eliminate glare; it diffuses it.  Second, when separated from the art even by the thickness of one mat, it blurs the artwork.  And third, it dulls the intensity of dark colors, so black will appear dark grey, etc. On the other hand, I have seen it used very successfully in a situation where otherwise the glare would have been unbearable, and where the artwork was a soft Chinese painting on silk, in which crisp detail and contrast were not important elements.

In addition to this conventional "nonglare" glass, there are now several kinds of optically coated, truly non-reflective or invisible glass.  These are excellent, but they are not widely offered and are still extremely expensive--about ten times the (frame shop) price of regular glass.  There is also the Uv-protective glass, which I discussed in the first section.

Then there is plexiglass.  Even if the price doesn't deter you, you shouldn't use plexiglass unless you have a very good reason to do so.  Plexiglass will warp on pictures of moderate to large size, and although this only occasionally poses a structural problem, it looks terrible.  In addition, plexiglass scratches easily, and cleaning it is troublesome.  The main use for plexiglass is for a picture that must be routinely handled or transported, and the owner prefers scratching to breaking.  Of course, plexiglass is also lighter than regular glass, but weight shouldn't be a structural problem in framing until the piece exceeds 36"x 48", in which case you will have to use plexiglass anyway because glass larger than that is generally unavailable.

There are also some practical considerations in the moulding choice.  Of course, your framer will let you know which frames are structurally able to support your work, and will provide any necessary reinforcing.  Professional fitting charges are usually lower for metal frames than for wood frames.  For the do-it-yourselfer, metal frames are much easier than wood ones to disassemble and reassemble if you have to fix something; all it takes is a big table and a screwdriver.  Most people do not have the right equipment to refit wood frames at home.  Metal is also a good choice if you know you will be moving soon or have to ship the framed art, since you can fairly easily slip the glass out, or insert protective cardboard around the glass, and reassemble the package for safer shipping. 

In addition, a framed artwork is meant to be hung on a wall and left there. So if your frame is going to get any unusual wear and tear, choose a durable moulding, either wood or metal.  If you are going to be transporting the piece much, or if it is likely to be in the line of fire of children, etc., avoid painted metal frames, which scratch easily and irreparably.  (A better option is one of the colored anodized metal finishes, which are much more durable; but although these finishes may be quite hard to scratch, once scratched, the scratch is hard to hide.)  Metal frames also cushion the glass less than wood ones, which means sharp blows to the side of a metal frame are more likely to result in broken glass.  On the other hand, occasionally you can replace a single scarred leg of a metal frame (or you can even repaint a metal frame with spray paint if you want to).  If you choose a wood frame, use a hardwood frame in a finish that will hide dents and will be easy to touch up if the finish is marred.  The other major weakness of a wood frame in terms of constant handling is its stretched backing paper, which punctures easily, but that is not a serious matter.