Restoration and Repairs

The value of an instrument is determined to a large extent by its condition. A soundpost crack in the back, for example, may reduce an instrument's value by as much as fifty percent. A broken tip will depreciate the value of a fine bow to a small percentage of its original worth. Less severe types of damage will have less drastic consequences.

Restoration will not reverse this loss in value, but it can return an instrument to its original condition in terms of sound, playability, and very often appearance. However, few repairs are truly permanent. Cracks may re-open. Invisible retouching may gradually become visible. Furthermore, bad repair work can cause long term damage far more serious than the original problem.

An understanding of the most common procedures used in restoration are a great help both in detecting repairs and in talking intelligently with the craftsman involved in any new work which might need to be undertaken. The following is a summary of the types of damage most commonly sustained by string instruments, and the techniques used to repair them.

Cracks

Because of the native fragility of the materials, especially the spruce, it is rare to find an older instrument entirely free of cracks. These cracks can be caused by the gradual shrinking of the wood over the years, or by a shock or blow to the instrument.

Cracks are glued (cleaning them first, if necessary) and then usually reinforced. When the crack occurs in the top or back, this reinforcement normally consists of a series of small wooden cleats glued across the line of the crack on the inside of the instrument. Cracks occurring anywhere near the bridge-feet or soundpost constitute a more serious problem and require the extra reinforcement of a patch.

Well repaired cracks may be invisible. Their presence can be deduced from the presence of the reinforcement inside the instrument. However, a cleverly hidden patch may be visible only to a well-trained eye.

Patching

A damaged area may require new wood to be put in, either to reinforce a repair, or to entirely replace damaged material. Patching involves the removal of a certain amount of wood from the inside surface of the damaged area. During this operation the area is supported with a cast made especially for the purpose. A replacement piece of carefully matched wood is then fitted and glued in. In the case of a soundpost patch, the new wood may go almost all the way through the plate, stopping just short of the varnish. In some cases, the patch goes right through, thus requiring both very careful matching of the wood and retouching of the varnish. This is known as a “through patch”. Patching is also used in the repair of broken buttons, some types of rib damage, broken ribs, woodworm damage, and in general when an area of wood needs to be replaced.

Half Edging

The careless opening of an instrument may result in the gluing surfaces of the top and back becoming chipped or eroded. Often this damage is simply smoothed over for re-gluing, resulting in progressively thinner edges. Repair involves gluing new wood to the underside of the affected area, thus restoring the edge to its proper thickness. The edges may have been worn down from the outside. Half edging in this case will effectively increase the height of the arching.

Half edging is visible at the joint between new and original wood. However if the new wood has been carefully matched and the retouching has been done well, the repair will be scarcely noticeable.

Plate Deformation

The tension of the strings, in conjunction with incorrect arching or thicknessing, inadequately seasoned wood, bad repair work (such as unevenly planed ribs), or improper set-up, can lead to bulging, sagging, or twisting of the plates. Although such deformation is correctable through plaster cast restoration, the process is long and costly.

It involves making a cast of the deformed plate. The arching of the cast is then corrected in slow increments, at each stage of which the original plate is gently forced against it, using heat to plasticize the wood. The plate is thus gradually restored to its original shape.

Acoustic Repairs

When the wood of an instrument has been thinned to the point that the sound or structure is impaired, new wood can be put in. This can take the form of patches or, more simply, stiffening straps. These are strips of wood glued in to add strength. They have the advantage over patches of not requiring the removal of any original material. They are also easily removable, should that seem appropriate at a later date.

Scroll

Damage to the scroll is most commonly caused by badly fitting pegs. These tend to be pushed in forcefully in an attempt to get them to hold. This causes increased wear to the pegholes and sometimes cracking of the pegbox wall.

When peg holes become enlarged due to wear, they can be filled in with new wood and then reopened. This is a process known as bushing.

Cracks beginning at the peg holes are first glued, and then the hole is bushed. The whole area is subsequently reinforced on the inside with a patch. Another method of reinforcing a crack in the pegbox wall is by the use of a threaded metal pin, which is counter-sunk into the wood and then covered over.

The majority of old violins had their original necks replaced when the so called ‘baroque’ set-up was superceded by the modern one. Many more modern instruments have also required new necks when their original ones became worn or damaged. The procedure for replacing the neck involves grafting the original scroll onto new neck stock. The joints of this graft are visible along the tops of the pegbox walls, and down their sides just below the lowest peg hole. One occasionally sees on copies of old instruments lines scribed in these areas to give the impression of a grafted scroll.

The Button

This small semi-circle of maple extending from the top of the back is particularly vulnerable to damage, as the area is actually weakened, rather than strengthened, by the purfling. It is for this reason that makers sometimes leave the wood around the button somewhat thicker, and Guadagnini at times even left the area unpurfled.

The base of the neck is glued to the button, the button becoming one of the principal gluing areas holding the neck in position. In the event of an accident where the neck is broken off the instrument, the button almost inevitably comes with it. After the button is glued back on it must be reinforced with a patch from the inside.

The button may become damaged when the neck is removed by an inexperienced repairman, or simply be worn down through long usage. In either case, it can be built back up with an ebony, or occasionally maple, collar. When ebony is used the repair is far from invisible. However, the black trim is often considered ornamental, perhaps explaining its widespread use.

Wood Worm

The larvae of this insect, actually a beetle, burrow through the wood just beneath the surface. They can cause extensive damage before any indications of their presence become readily visible. Telltale signs are small pin-size holes where the larvae enter, and somewhat larger holes where they exit. Wood dust left by the insects may be noticed. Instruments in storage are far more susceptible to infestation than those being played.

Wood worm, once detected, can be eliminated by fumigation or radiation. The extent of the damage can be accurately assessed by x-raying the instrument. Repair involves a combination of filling and patching, work which is time consuming and very difficult to conceal. In cases of extensive damage the instrument may not be not worth repairing.

Glue

The most fundamental material used in restoration is, of course, glue. The principal glue used for both instrument making and repair is hide glue. It is made from animal skins and is used hot. It has the quality of holding securely for long periods, yet releasing cleanly when necessary. This is extremely important. Almost any of the joints may need to be opened during restoration, and it is essential that this can be done without damage to the wood. The presence of an inappropriate glue can make a simple repair into a major operation.

The glue also acts as a safety valve – if its strength is well judged it will give before the wood cracks. A rather thin mixture is used in gluing on the top, as the top will sooner or later need to be removed. The center joint, on the other hand, calls for the strongest possible mixture.

More permanent glues, such as casein and some synthetic varieties, do have their place in restoration. For example, hot glue will not reliably hold the pernambuco wood used for bows.

Blacklight

Many of the materials used in varnishing and retouching have the property of fluorescing distinctively under ultraviolet, or “blacklight.” Repairs invisible in daylight may become obvious when so viewed. Experts sometimes make use of this phenomena when determining the origin or condition of an instrument, and restorers find it useful when removing coatings of inauthentic materials.

Composite Instruments

An instrument incorporating parts not made by the original maker, or parts garnered from different instruments by the same maker, is known as a composite.

There are various reasons for the existence of composites. At one time makers would have made a new top as soon as repaired a badly damaged one. In fact, the art of restoration developed rather recently in the history of instrument making. But even today new parts may be fabricated when damage to the original ones is irreversible. A less innocent source of composites is the pirating of parts from one instrument in order to make another one more valuable. Whatever the story behind an unoriginal part, it may take an expert to spot its presence and to assess its impact on the value of the whole.

Philosophy of Restoration

Any restoration should be done in such manner that, to the greatest extent possible, it can be undone later on. Few repairs are truly permanent. Many will need to be done again at some point in the future, and by then there may be better ways of doing them.

One of the parameters for judging the quality of a repair is its current invisibility, another is how long it will stay that way. As Charles Beare once said, “A good repair is invisible, a great repair is the same thing fifty years later.”

And yet the philosophy and ethics of art restoration are by no means simple. There are ethical considerations involved in making any repair not just invisible under normal circumstances, but completely undetectable.

Unless an instrument is kept in a museum, some wear to the scroll, edges, corners, and varnish is almost inevitable. This will affect its value to some degree, however the extent to which such wear should be restored is sometimes a delicate question. Bringing an instrument back to mint condition means, in a sense, denying its history. Taste, along with a respect for the integrity of the original, must always be the final guideline.