Yet again, your fearless site administrator has decided to wade into controversy, this time to tackle the subject of refinishing square pianos! Whether we emerge ‘unblemished’ will depend on the quality of the input from others, and here is a subject that almost everyone feels entitled to speak on.

We will separate this from the larger issue of Restorative Conservation which has its own page now, and just speak on the finish elements we find in early pianos. Before we go further, consider that the finish of the piano as you find it is a historical document, regardless of how attractive, and just altering it to make it ‘pretty’ really is simply imposing your values on the piano. But we also know that not all of recorded history is particularly valuable, so read on, as we treat ourselves to the full spectrum regarding this subject.

I think it should go without saying that if you have just acquired a square piano that was ‘in Farber House, kept under the stairs since 1820 and never messed with’, meaning it is in pristine condition, that we won’t need or want to touch the finish. Similarly, if you have the very piano that PDQ Bach wrote Ring of The Beer Mug on, we will leave those white circles alone! Similar for pianos featuring chinoiserie or other decorative painted surfaces.

Stodart square decoration

Noted restorer Graham Walker has put all this quite succinctly:

“The first point that I would make on this subject is that we need to advise a newcomer to avoid making an immediate decision to remove and replace a surface finish on a square piano because there are a few blemishes.  I know that I have made this mistake in the past, but I now examine a surface finish very carefully with the aim to do the minimum possible to achieve an acceptable finish.  If we try and define an acceptable finish, it will vary. If a piano is going to be part of a museum collection it will probably be left untouched, but if in a domestic environment it will generally need to look reasonably good to fit in with other furnishings.

The approach that I take is to consider a number of possible actions, each one being a little more progressive than the previous one.  My view is that it is more desirable to have a square piano with marks, blemishes and variations in colour and appearance than one that has been stripped and re-polished.  The latter has not only lost its evidence of age but actually is less interesting.   There is also another factor that I am unable to describe, but sometimes I see a piano in the auction room that is generally untouched, that gives me a true sense of age and I find very appealing, but in another example that had been interfered with, this factor is completely gone. “

If a complete refinishing is not suggested, there are any number of commercial products and waxes that purport to be restorative. I have had good success with microcrystalline waxes, but avoid products that leave a sticky oil behind such as citrus oils, or truly awful products like Old English. On the subject of restorative polishes, David Hackett advises:

None of us has ever seen an English square piano as it left the workshop/factory.  Surely all of them will have been vigorously polished (beeswax?) by parlourmaids or proud owners – but mostly on the outside? It is an observation that the insides of most lids are (now) less ‘finished’ than the outsides, as are internal bits like damper-covers, internal edges, etc.

On old pianos, I have done very well with my ‘Secret Recipe Magic Restorer’:

2 parts real turpentine (not white spirit)

2 parts vinegar

2 parts linseed oil

1 part ethyl alcohol/IMS

Shake before use.  Looks like French Dressing, but not good on salads. Used with cotton rags or 0000 steel wool at first, and with patience over several days, it removes dirt, dirty wax, etc. and revitalises what polish is there.  I suppose the alcohol softens any shellac, and the oil builds a finish of its own.  The turpentine will soften/remove old wax, and the vinegar cleans off the dirt.  The rags certainly get pretty skanky!”

To this Graham adds –

“As you will know, very few square pianos just have their original finish and most have, at least, received an added coat of shellac in the 19th century or later but still may exhibit a good patina and most should be left untouched.  As David has said, using a surface cleaner may be sufficient to give acceptability of the surface finish.  Sometimes there is so much “gunk” and dirt within the finish that I believe it is justified to remove with a soft polish remover.   The surface can then be waxed or it may be necessary to reseal with a thin coat of shellac and wax.   If something stronger is necessary to remove the surface finish, I use methylated spirits but not varnish remover, except in very extreme cases.  Sanding the surface should be avoided as some aspects of the patina will still be evident.   I think that we have all developed our own variation on a theme for the method of surface finishing. I’m not an expert but I use a sanding sealer, followed by shellac, (but this should remain a low build on the surface) and then wax.   In addition, I have also used fine balm oil that somehow gives a maturity to the finish. “

For our square piano finishes, we should then proceed in a thoughtful fashion with an eye towards achieving as authentic a completed instrument as possible. We are told repeatedly that refinishing a piano hurts the value, and in the examples above this is true. But in reality (aside from an astonishing amount of general restoration needed!) the value of the run-of-the-mill average square at auction is reduced by a poor condition finish from decades of abuse, or a bad/unauthentic refinishing job that has left the piano covered in a sort of modern plastic wrap, or worse, has itself started to alligator or brown and must be removed. Museums are not acquiring squares much these days, and those that are, get them from other museums. What we want in our house then is an instrument that presents well and plays, preferably with as authentic a character as possible.

unrestored Longman Broderip

So what is an authentic finish on an 18th century square piano? I’m glad you asked that question, now prepare yourself for an equivocal answer. The best response is “it depends”. It does indeed depend on the maker, the year it was made, and the social status of the intended customer. The finish used for the plain little Longman and Broderips was apparently kicked up a notch for their pianofortes in the fancy style, while other makers adopted a more conservative approach in line with their building philosophy, or routinely pulled out all the stops. David Hunt observes distinct variations in the finish of name boards and stands VS cases, as have I in the case of a Longman and Clementi in my possession. The name board is obviously more heavily varnished and made to appear glossy as opposed to the case, and this piano came to us in very well preserved condition and provenance that strongly suggested little intervention.

There is no reason to believe the piano trade followed the furniture trade practices exactly, but many of the builders trained as joiners first and would have been intimately familiar with traditional finishing techniques. That said, the instrument trade had developed in parallel, and there were specific varnishes for string instruments that were rarely used on case goods, for instance. Pianos fit somewhere in the middle, being neither a traditional case good nor needing the approach of a stringed instrument.

We can look at the finish as a layer cake. Life starts with the wood, which must be sawn and planed, then is joined and given a final finish surfacing. Generally this consisted of using a cabinet scraper to develop a smooth surface, though a sharp plane left a fairly nice finish all its own. Sanding at this stage was largely unknown, and abrasives were generally used later in the process we describe, in the cutting back of the varnish stage.

Once smooth, the wood pores must be filled. Just coating over the wood will leave an uneven hazy appearance that on close inspection reveals the pores in the wood. These would fill with dirt and leave a very unappealing surface with time, which we never see today. Mixtures of pumice, wood dust and glue (see Roubo, L’art du menuisier), or brick dust and linseed oil (see Sheraton, Cabinet Dictionary) rubbed in with a cork block, were prescribed for filling pores. The purpose was to fill the pores with a material that was either transparent or the same color as the base wood, and that would not shrink or bloom on final finishing.

Now that the wood is smooth and pore free, it might be stained or dyed. These are sometimes revealed when a bolt cover or name plaque is removed, revealing a deeper toned wood beneath, where the dye has not yet faded. Pigmented dyes thoroughly penetrate the wood; pigmented stains typically affect only the top surface. Preserving what remains of a stain or dye is critical to an authentic final look. Similarly, the pore filler can be completely removed when varnish strippers are employed. This is why the use of harsh strippers is to be avoided. Let us remove no more of the finish than is ever required to return it to a state of grace.

The next layer is a varnish or wax. Varnish may be either spirit based (alcohol spirits with sandarac, shellac or similar dissolved in) or oil based, including walnut and linseed oil. Not surprising, hardening and coloring additives such as copal and amber might be added, while an oil and spirit varnish might be combined in one operation.

Sandarac is a brittle pale yellow resin from northwest Africa, from the Thuya tree Tetraclinis articulata or Callitris quadrivalvis. It is the hardest of the spirit varnishes, so copal or mastic were often added to increase elasticity and prevent instant marking on  casual impact after it is dry. These varnishes cure by evaporation of the solvent, which with alcohol is rapid. The down side is that application time must be strictly controlled and broad surfaces present a challenge to master without streaking. It is soluble in alcohol as is shellac. In the Treatise on Japanning and Varnishing, by John Stalker and George Parker, 1688, we find that they recommend “Best White Varnish”, made up as:

Spirits of wine, which must be strong or you will spoil the varnish. The recipe calls for separate solutions of the following in spirits of wine:

  • Gum Sandrick 1lb
  • Gum Mastick 1 oz
  • Gum Copol 1 1/2 oz
  • Gum elemni 1 1/2 oz(gum Anime from the Courbaril tree)
  • White rosine 1/2oz.T

Preparation mixed with 3 oz of Venice Turpentine form the famous white varnish.*

This was a popular varnish throughout the 18th C. It means that not all alcohol varnishes found today are of later origin.

Shellac is the product of insect egg casings. While used throughout the 18th century, it was not until the early 19C that refinement of shellac was brought to an art. French Polishing, the art of applying shellac based varnish with a linseed soaked rag to build up a mirror finish, was indeed a product of the middle years of the 19C. When we encounter an alcohol based finish on a square piano today we are likely to feel it is a later application based on French polishing, but this of course is not always so.

Fixed oil varnishes, or resin/oil varnishes were very popular, and perhaps the most commonly encountered in 18th and early 19th C square pianos. Linseed oil was used in abundance, atypical oil varnishes went something like:

Turpentine to oil 2/1 mixture

  • 90% pine resin, 10% gum benzoin
  • Linseed oil
  • Lime
  • Turpentine
  • Add pigment material for desired color and effect if needed.

    This varnish cures by oxidation rather than evaporation, so a clean shop where the varnish can cure for many hours is required. however, application without streaking is more easily achieved, so mastery of the art is less involved. Its popularity was widespread, not only for pianos. It is a durable and long lasting finish, though not so bright as sandarac.

    The varnish would be ‘rushed’ or cut back to preserve clarity while bulding up the required number of coats for a bright flat finish. This was also called ‘rubbing out’ and when done properly built a fine finish, not quite so mirror like as French Polish, but with such a combination of shine and sheen that it produced a striking effect on the brightly colored woods of the time.

    However, there is evidence that in lieu of a true varnish, some pieces of woodworking were finished in a simple wax and turpentine coating. This produces a very soft finish, possibly suitable for an object that was intended to receive light duty. A few restorers and square piano enthusiasts report having come in front of instruments with only a wax final finish. The majority though, seem to have used more robust finishes as described.

    Finally a polish was applied as the final coat, usually of pure linseed oil or beeswax in turpentine, to even out the last imperfections. This could be renewed as often as wanted.

    We now come to the matter at hand, that of the square piano in need of attention. As we heard from Graham and David above, an approach that is graded seems most prudent. An initial cleaning with a damp, not wet, cotton cloth and a product like saddle soap which is both mild and easy on surfaces will reveal the nature of what is left. A good finish comes up nicely after the cleaning, and if it develops any haze after drying it suggests that a rewaxing might be enough.

    Next we might try a little turpentine on a cotton cloth in a non-obvious spot. Look for removal of finish or any softening. If none (and there should be none) you can explore more areas for effect. In the past I have thought that typically, this has little value. A recent experience with a Broadwood grand of 1791 revealed a layer of something like lemon Pledge, that came up with pure turpentine, and left the finish in a far more life like state. Turpentine DOES have its place! Mineral spirits had little effect here, so consider the smellier but more powerful turpentine appraoch.

    Next we would turn to alcohol, methylated spirits, or methanol in the USA. Again sample a spot for effect. If you remove a layer of varnish leaving behind a shiny undersurface, it has a top coat of shellac applied and removal might be a consideration. If it leaves bare wood behind, it might be an original coat. Judgement here will fall on the side of what will create the most most pleasing overall effect.

    If the finish is shot, flaking, lost in wide areas, damaged beyond hope, then removal is appropriate for pianos whose value is to decorate our homes and bring enjoyment. We DO NOT want to remove the filler or even the stain if at all possible. So we need a solvent to remove varnish only. This is tough, as the fillers are usually soluble in the same solvents as the varnish. The approach then is to go light, quickly, and let up before we get into it too far. Using a solvent system with multiple components is one way to approach this.

    Methylene chloride is found in almost all commercial strippers, for the reason that it works so well. At full strength it is so effective that everything will be stripped out all at once. Co-solvents such as acetone, toluene, isopropyl alcohol, and such can reduce the stripping power while softening varnish. We want to avoid most of the powerful strippers, but a product like Formby’s Refinisher is a multi solvent system suitable for careful work. Further cutting with alcohol will improve control.

    A three part ethyl acetate, alcohol, and acetone mix is particularly good for removing only a top layer. However, formulating your own stripper carries certain risks. Proceed at your own judgement.

    For name boards that have ink inscriptions, there is no safe way to proceed. A light wax and leave alone is best. If inlay is present, proceed only with the lightest touch, and stop well ahead of a full finish removal. I personally leave name boards completely alone, and have yet to put solvent to one.

    For those wishing to replace a varnish with one of the historical blends I suggest:

    James C Groves for a variety of prepared varnishes

    Sanders Studio for recipes towards making your own

    *Thanks to Leroy Douglas Violins for use of these explanatory bits.

    Benzoin (Gum Benzoic or Benzoe)
    (1) A balsamic resin obtained from Styrax benzoin, a tree native to Java and Sumatra, and from other varieties of the Styrax;
    (2) the Lithocarpus benzoin, a tree found in Thailand. The Thai benzoin occurs in the form of small “tears.” This Thai benzoin is reddish-yellow to white in color, consisting of 10-14 % benzoic acid, and the rest resin. The Sumatra benzoin occurs only in masses of dull red resin enclosing white tears.

    Copal, from the Mexican copalli, incense, is a hard, lustrous resin, and the term is generally and vaguely used for resins which, though similar in physical properties, are altogether distinct as to their sources.
    Mexican copal, generally considered the best, is obtained from a species of Hymenia. It is tasteless, odorless, almost colorless, transparent, and lemon-yellow or yellowish-brown in color. It forms one of the most valuable of varnishes when it has been dissolved in alcohol, spirits of turpentine, oil of turpentine which has been exposed to the air, or any other suitable medium. The addition of oil of spike or rosemary promotes its solubility in alcohol. As a gum it ranks next to amber in hardness. Copal is also obtained from Sierra Leone, and in a fossil state, from the west coast of Africa, as well as from Brazil and other South American countries, from trees of the Guibourtia, Trachylobium and Hymenia families.

    Anime is the hard copal resin obtained from the Hymenia courbaril, a South American tree; while gum anime is the name also given to the resin known in commerce as Zanzibar or East African copal. The raw copal yielded by Zanzibar Trachylobium hornemannianumis inferior, and used only in India and China for making a coarse varnish. The fossilized East African copal is dug from the ground over a wide belt of the mainland coast of Zanzibar. A gum obtained from the Vateria indicais also known as gum anime, and is often confused with true copal in commerce.

    Elemi (Gum Elemi)
    This is a fragrant resin obtained from the Egyptian Amyris elemifera and the Mexican Elaphirium elemiferum, and is greenish-yellow and semitransparent. The oleoresin known as manilla elemi is obtained in the Philippines, probably from the cananarium commune, is pale yellowish color, and is soluble in alcohol. In the 17th and 18th centuries the term elemi usually denoted a Brazilian elemi obtained from trees of the icaeiu species.

    Mastic (Gum Mastic)
    A resinous exudation from the lentisk, Pistacia leatiscus, the evergreen shrub, tree, the mastic gum comes from the resin that seeps like teardrops from the bark.  Found in the Mediterranean, particularly in Greece on the Aegean island of Chios; also along the coast of Portugal, Morocco and the Canaries. Mastic occurs in commerce in the form of roundish tears, transparent, with pale yellow or greenish tinge. It is soluble in alcohol and oil of turpentine.

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