Preserving Paintings: Before and After

A Question of Responsibility

by   Peter Kostoulakos

Who is responsible for the preservation of a painting - the artist or the collector? Before an answer can be given to such a question we should explore the term "preservation" as it relates to a work of art.

The preservation process does not start at the time of completion, nor when the painting reaches a matured state. It starts at the very beginning of its creation with the use of properly prepared materials, sound technique, a protective varnish layer and framing. This, of course, is the responsibility of the artist.

When the ownership of a painting is transferred to a buyer or collector it is then his or her responsibility to oversee placement, hanging, care, cleaning and conditions of climate. These are all factors of preservation.

It is my belief that most artists are truly concerned with the longevity of their work and take pride in all aspects of its production. After all - if the artist displays little concern or respect for his artistic creation then how can a collector be expected to!

Painting is a craft - a developed skill involving intellect as well as emotion - but it is also a profession and artists should be professional in their choice of materials and techniques. This starts with quality canvas stretched over a well constructed "stretcher" frame capable of being "keyed" out at 45 degree angles. Some contemporary painters try to economize at this point by stretching low grade canvas over homemade "strainers". A strainer is a frame that is joined fast at the corners and cannot be keyed out to create a taut painting surface. This induces "sagging" and "draws" from the corners which in turn hastens the cracking and flaking of a painting.

Some artists of the not too distant past used high grade fabric and stretchers and then, to save a few pennies, primed their canvas with ordinary house paint. "Sizing" and "priming" a top grade linen when preparing a canvas are major steps in preserving paintings. The paint layers, or image we see and appreciate are resting on this foundation and, if the foundation is weak the structure crumbles. If an oil based primer is going to be used the fabric should first be sized with rabbit skin glue. This separates and protects the fabric from the oil. Linseed oil, when allowed to come in contact with raw (linen) canvas, will dry out and eventually rot the fabric.

One of the most important considerations for creating well preserved paintings is technical procedure. There are many philosophies on the subject but one of the most basic, yet essential, procedures is for the artist to paint FAT over LEAN. Lean paint has less oil content than fat paint. Thinning the paint with turpentine results in a leaner, faster drying and toothy surface for subsequent paint layers. Sketches and underpaintings should be done with a lean paint mixture. When an artist paints a lean, fast drying layer over a fat, slow drying layer tension is created. The fat layer, if not completely dry, moves during oxidation and cracks the stiff, lean paint layer. Lean paint will slide or "crawl" over fat paint as it dries leaving an "alligator" pattern of cracks that greatly disrupts the composition and intended mood.

When the painting is thoroughly dry and complete in all details it must receive a protective coating before being placed into a frame. Oil paintings require four months to a year to be dry enough for varnishing while acrylic paintings can be varnished the same day they are completed. There are many varnishes on the market - some made for fine paintings and some made for furniture, floors, and boats. When necessary a picture varnish can be removed and a new coat reapplied without harming the painting. Wood varnish, on the other hand, cannot be removed without the use of harsh solvents and scraping. Varnish for paintings should be purchased from an art supply store - not a hardware store! A prerequisite for all artists' varnishes is that they must be easily removed without harsh chemicals or solvents. This means the chosen varnish must be soluble in turpentine or mineral spirits for natural resins or xylene or toluene for synthetic resins. Hard resin varnishes prepared in oil, such as copal and amber, should be eliminated as picture varnishes. Their strong, inflexible films can be a destructive influence, rather than the protective one it is intended for. Two commonly recommended varnishes are damar (natural, soft resin) and methacrylate (synthetic, acrylic resin). When the ravages of time, dirt and atmosphere render them fragile and inefficient they are easily removed with mild solvents. Under normal conditions a picture varnish should stand up structurally and aesthetically for at least 25 years. To summarize this important step in preservation: always varnish paintings so the varnish, not the painting, receives the brunt of all blemishes; use a soft natural (damar) or synthetic (acrylic) varnish that can be removed without harm; and apply one to several thin coats rather than one thick coat.

Framing is usually thought of as a decoration only but it is a major and vital step in the preservation of paintings. A well built frame stops the auxiliary support (stretcher) from warping thus eliminates the tears and cracking produced by the movement of a warping support. Many contemporary paintings merely have molding or trim tacked to the stretcher. This can be, at times, aesthetically correct but it is never structurally correct and should be rectified before hanging for permanent display. The frames inner measurement, or rabbet, should allow for some expansion and contraction of the painting. A painting should never be forced into a frame, trimmed to fit a frame, or attached by hammering nails through the stretcher and into the frame. Mending plates or "spring clips" should be placed over both the stretcher and the frame but only secured to the frame with screws. Reputable framers know, and use, sound framing techniques.

Most conservation needs are a consequence of two things - the touch of a well-meaning admirer and the myths related to art restoration. Painting restoration is an antique term which, to some, refers to the way artists used to completely refurbish paintings. The painting was not preserved but only made to look new again. Sometimes the painting was completely repainted covering up the artist's work. Painting conservation, today's term, refers to the restoration and preservation of the work with the greater importance placed on preservation. This is accomplished by careful examination and testing before any cleaning and repairs are made and, when retouching is necessary, it is applied to the damaged area only. Whichever term is used, restoration or conservation, the essence is, or should be, the same.

The rubbing of linseed oil over an old, dry, cracked painting to revitalize it is one of the most destructive myths in use today. Linseed oil does not penetrate, soften or revitalize dry oil paint. It merely streaks the grimy surface and dries to a heavy, hard, discoloring layer over a dirty, cracked, discolored layer.

In summary, preservation starts with the purchase and preparation of quality materials; the knowledge and skill of the artist; a protective varnish coating; sound framing methods; climate controlled atmosphere; and, above all, the thoughtful consideration of both artist and collector. Preservation is an ongoing, never ending process that is the responsibility of the artist, the collector, and anyone who handles art.

A "Behind the Scenes " Look at Oil Paintings

by   Peter Kostoulakos

As fine art enthusiasts we all, at times, fall under the emotional spell of the bright colors and moving lines of a particular composition, yet there is more to a colorful scene than a visual image. A "behind the scenes" investigation will tell you a great deal about the prospective painting. The name of the artist, title of the painting, canvas maker, date of canvas and stretcher, exhibitions and former owners are some of the things that may be revealed upon closer examination.

Whether the painting is a portrait, landscape, or still life— if we like it, we want it. And after all, isn't it the intent of a painting to provoke an inner excitement we call instinct or taste? The answer is yes, we should enjoy, if not relish art. However, when buying an antique painting, as with any antique, a detailed on-the-spot, examination should take place. Sounds too complicated, you say? Not at all. A small checklist covering composition, support, paint layers, varnish and frame is all that is needed.

The first part of our checklist examination is easy for it deals with composition, and as already stated, it is a matter of personal taste and enjoyment. In addition to enjoyment, keep in mind that paintings, especially landscapes, possessing bright, cheerful colors will usually command the highest prices because of popularity; a portrait or figure painting of a woman will usually sell faster than a portrait of a man unless he is elegantly detailed and surrounded by character revealing objects or important documents; and portraits of children, alone or grouped, seem to be enjoyed by many.

Size must also be considered at this time. The small and medium sized easel paintings are more practical in today's home, thus more marketable than the larger full-length portraits and landscapes usually seen only in museums and public buildings. Bigger does not always mean better!

Next, turn the painting over and examine the "support." This is the material on which the picture was painted. The most commonly used supports were, and still are, fabric (linen), wood, and a combination of the two. Other types have been used but present deterioration problems.

Examine wood panels for worm holes, cracks, sealing material, hardware and, of course, any markings or labels that aid in revealing provenance. If the back of the panel is not properly sealed, moisture will be absorbed from humid atmospheres causing swelling and, in arid conditions, drying and shrinking will occur. Moisture absorption is detrimental to wood. It causes a concave warping that, in time, forces the paint layers to lift and push together in a "tenting" formation. Drying out causes a convex warping movement that pulls at the paint layers, causing them to crack and separate thus producing gaps in the original composition. Both conditions can be treated but the process requires a great deal of time and expense.

Changes in environmental conditions create a back-and-forth movement most inflexible, antique paint films cannot endure for too long a time. The atmospheric changes discussed here are not necessarily geographic. Paintings from a hot, dry attic to a humid basement, or those hanging near a door or over a fireplace, undergo severe atmospheric changes. These changes will move the support and paint, which will eventually damage the structure and distort the image.

Panels that are held fast to the frame by nails, screws and mending plates are in danger of cracking, or "checking," because wood panels, especially thin ones, have a tendency to move. Securing the panel tightly to the frame to discourage movement will do more harm than good. Remember, it is the lack of sealing material on the back of the panel plus the changing atmospheric conditions that cause the panel to warp. Placing extra strain on the panel with the wrong hardware will cause it to check or split completely along the grain. If tension is obvious, conservation work will be required and must be a consideration when determining the price of the painting.

Pictures painted on fabric will require a secondary, or auxiliary support. This is the wooden frame the canvas is stretched over and tacked to. Basically there are two types of secondary supports —"strainer" and "stretcher." The strainer is the older of the two and, for its purpose, it is very poorly designed with fixed joints held fast by nails and/or dowels. The half lap, or ship lap, was the simplest and most common during the 18th century. Variations of the mortise and tenon were also used at that time but were not common until after 1800.

The stretcher appears in America in the late 18th century. This is a much better design because the joints are expandable, which keeps the canvas taut. This usually reduces the amount of conservation work because a taut canvas doesn't wrinkle and distort the paint layers.

Stretchers have two triangular wedges, or "keys," placed in the angle of each corner. As the keys are tapped in, the corners separate slightly and the canvas support becomes taut. When the humidity and temperature change, the whole painting moves. A rise in humidity causes the support to swell and become slack while a lowering of humidity causes it to contract. This constant expanding and contracting of the canvas may eventually lead to a warped stretcher, torn canvas, cracked paint and paint losses. This action may also loosen the keys and cause some of them to fall out. When keys are missing, check the bottom of the painting between the canvas and the auxiliary support. This area seems to be a catch-all for other debris too and, if objects are allowed to remain, they may damage the painting. Missing keys should be replaced as soon as possible to keep the canvas taut and wrinkle free. The keys should be lightly tapped into place taking care not to touch the canvas or cause a sudden shock to either the canvas or the paint layers. If an aged canvas is stretched too quickly it will tear.

The most commonly used corners for stretchers are miter, half-miter, and butt-end. The miter corner is made by placing two 45-degree, slotted angles together creating a perfect 90-degree corner. The butt-end corner is comprised of two 90-degree, slotted angles butting together to make a 90-degree corner. The half-miter is a combination of the miter and butt-end. It appears to be a butt-end from the back but the side hidden by the canvas is mitered. With the miter corner the expansion and contraction movement is even, therefore superior to the uneven, side movement of the butt-end corner. The auxiliary support should be beveled on the side that faces the canvas so the innermost part of this wood frame does not crease the canvas. Because the butt-end has an uneven movement, it can cause wrinkles or "draws," in each corner of the canvas. If the draws are allowed to remain for a period of time the paint layers will harden to their form, become difficult to remove, and may disfigure the painting.

>The most common support is linen. After it is stretched, sized with animal glue, and primed, it is usually referred to as "canvas". When the artist prepares a canvas as mentioned, it is referred to as artist primed or artist ground. When the canvas is prepared commercially it is referred to as preground or preprimed. Commercially prepared canvas was often stenciled or stamped by the manufacturer and/or seller . Stencils are helpful in authenticating date and place of creation. As canvas makers and sellers changed locations they changed their stencils. Therefore, if the selling date of the canvas can be established by tracing the stencil to a specific location, a starting for the paintings creation is also established. In other words, if an unrestored painting is signed and dated by an artist who died in the year 1850 but has a stencil on the back used by the manufacturer and/or seller from 1875–80, 25–30 years after the artist's death, the painting is an obvious fraud.

The physical structure of the canvas should also be examined. The inside edge, partially hidden by the frame, is called "tacking edge" because it is the edge used to secure the canvas to the auxiliary support. Wooden tacks will usually be found on works completed during colonial times. Before the 18th century wrought tacks were a luxury few artists could afford.

The tacking edge reveals quite a bit about care in preparation. If it was left raw, or unprimed, most likely it was prepared by the artist. If it was primed and the tacks were not covered with primer it was commercially prepared. When tacks fall out or placed too far apart the canvas support can develop something called "scalloping". This is a result of fabric shrinkage between tacks placing a great deal of tension at the tacking point. Permanent damage and disfigurement may result if the condition is left untreated. The older the painting the more dried out and vulnerable the canvas will be. Trying to stretch out the scalloping will tear the canvas at the crease on the tacking edge; therefore its treatment is for experienced hands.

When the original tacking edge is missing, the back of the canvas appears to have a brownish coloring, and the edge is covered with tape—the painting has been "lined". Lining is the process of attaching a new piece of raw linen to the back of the original canvas. This process is used to strengthen a weak support, repair tears, and bind loose pigment. Canvas and oil paint are organic materials that break down with age and, to secure longevity, must undergo the lining process at some point in time.

The paint layer really consists of several layers of paint: strong layers, weak layers, flexible layers, brittle layers, etc. Its condition depends on two major things: how the artist constructed the total painting; and how the painting has been cared for since its completion.

Cracking and paint losses are often very apparent but sometimes a careful examination is necessary. When possible, hold the painting up to a light source such as a lamp, window, or direct sunlight. The painting should be far enough away from lamps or windows to avoid contact but close enough to allow light to show through the cracks. Handle the painting carefully! Sometimes sections of paint are extremely loose—held only by a thread—and improper handling will result in paint loss. Oil paint moves during the drying process, shrinks, and becomes brittle with age—thus "age cracking" is unavoidable and a display of antiquity that should be secured but not disguised.

The type of cracking you should be concerned with is cupping,curling, lifting and separating from the support and/or ground. A light source placed at an angle to the painting will create a highlight and shadow pattern wherever these irregularities exist. This is known as "raking light illumination" and, in addition to being a quick and easy examination, it is very informative. If the raking light reveals this type of cracking and separating, the best remedy is to line the painting with an adhesive that will consolidate the defective areas.

Oil paintings are usually protected from dust, grime, soot and other environmental conditions with varnish. When varnish ages it becomes brittle, it cracks and it turns from a transparent coating to an obscuring yellow-brown coating: it dulls the paintings color, reduces visual depth, and loses its ability to protect the painting. A bluish white cloudiness, called "bloom", is another common varnish ailment. It is caused by minute fractures and further deteriorated by moisture. When varnish discolors and cracks it destroys the appearance of a painting and it loses its effectiveness as a protective coating. This discouraging condition is as temporary as the varnish coating and, if you like the painting, its purchase should not be ruled out. Picture varnish can usually be removed without too much difficulty by a paintings conservator. A day or two after varnish removal a fresh coat should be applied to ensure future protection as well as restoring the natural coloring and visual depth to the painting.

The last part of our checklist examination will deal with the frame for it is the last, and most neglected, step in the preservation of a painting. Framing is usually thought of as a decoration only but its primary function is to house the painting. Some of the newer frames are not strong enough to support the painting and, unfortunately, the reverse effect is true—the painting supports the frame. Antique frames are usually built heavy enough to discourage warping of the auxiliary support thus eliminating tears and cracks produced by such movement.

Check the screw-eyes. They should never be attached to the support. Some artists do this for exhibition purposes and somehow they remain to do a great deal of damage to the picture. Imagine the effect of a light, fragile stretcher supporting the weight of a heavy frame! The proper size screw-eyes should be firmly attached to the frame only! The total weight of the frame work will determine a suitable gauge picture wire. If the wire appears to be old and weak, have it replaced. I have seen too many paintings very badly damaged because of an attempt to retain original screw-eyes and wire. What a shame! The placement of the screw-eyes and the length of the wire should allow the painting to hang slightly forward. This softens glare, keeps some of the dust from accumulating on the surface, and permits air to circulate around the painting.

And finally, before you place your new investment on the wall, check the picture hanger to see if it is firmly planted. Now relax and, with peace of mind, enjoy your antique painting.