Finishing the surface -- prep sealer, oil varnish, and polish

    The arcane art of finishing a luthier family instrument and the mystic surrounding this process is legendary. This process is not the same as for finishing furniture. A musical instrument wood must remain unspoiled and untainted so it can develop. The cells of the wood contain pitch. As this pitch dries it crystallizes and leaves the cell nearly empty. This is why instrument makers pay large prices for aged wood, and is one of several reasons that in instrument gains tone and voice as it ages. This process takes about seventy to one hundred and fifty years to achieve. Certain treatments enhance and strip the pitch from the cells wood allowed to soak in the bay of Verona for two to ten years allowed tiny microscopic sea animals to eat the pitch out of the cells. Some wood cut a century ago in Michigan, sank into the great lakes and was rediscovered recently. This wood, from the lake, also has the property of empty cells and is drawing a big price from luthiers. If you pay a big price or not, one does not want to spoil the potential of an instrument by gumming it up with oils or other foreign substances. The surface of the wood must be sealed, to prevent contamination of the cells. Sealing is done in one of three ways:

Coating the surface with a thin coat of instrument making glue using a shellac. (Spirit based component that seals and does not sink in the wood) using sizing.

I prefer the shellac sealant over the other two options the glue is not as good at preserving a clear vision of the wood (gets cloudy or dark) tends to be brittle and hard too the sizing does not stick well to the oil varnish and it tends to sluff off or become gooey over time. The protective coating of sizing, shellac, glue, must be nearly removed after being applied until just enough remains to seal the instrument and provides a base for the oil varnish.

Once the surface is sealed, the oil finish can be applied. Here is a listing of period recipes for instrument grade varnishes along with the source. I have experimented with some of these and have developed what I find to be a good varnish for musical instruments out of this information and some other source books I have one 16th century violin varnish. These are as early as the documentation on varnish gets. A couple of 15th century recipes have been found but their application to musical instruments is dubious:

The following is an excerpt from: Marryfield P. Mary, 'Original treatises dating from the XII-XVIII centuries on the Arts of painting', 1849, London

1.   Jehan Le Begue Ms, 1431. 1.Recipe no. 117: "Azzurrum sic fit".

Contains a recipe for varnish: ‘…put the mastic and varnish (sandarac) in powder into the oil (‘olei communis') and stir it well with a stick, and when you see that they are dissolved, add the Greek pitch in powder, and let it boil a little, until the whole is incorporated. … Let it stand for three days.'

2.   Eraclus Ms, dated 15c. 2.'How to varnish gold so that it will not lose its color. - If you wish to varnish gold that has been laid upon gypsum, varnish over the gold, not with pure varnish, but with that color which is made for preparing auripetrum, mixed, however, with oil, and a little varnish, lest it should be too thick. … But you may varnish figures and other colours with pure varnish or with thick oil.'

3.   'How wood is to be prepared before painting on it. - Whoever wishes to adorn any wood with divers colours, let him hear what I say. First make the wood very flat and smooth by scraping it, and lastly by rubbing it with that herb that you called shave-grass. But if the piece of wood is such that you cannot smooth down its inequalities, or you have reasons for not wishing to do so, and at the same time are not willing to cover it leather or with cloth, grind dry white-lead …, but not so finely as if you were going to paint with it. Then melt wax over the fire in a vase, add tiles ground fine. Then mix it with the white-lead which you have ground, stirring it frequently with a small stick, and so let it cool. Than heat an iron, and with it melt the wax into the little fissures, until they are level, and than scrape off the rough parts with a knife. … And when you have made it smooth, as I was saying, mix plenty of white-lead very finely ground, with linseed oil, and lay an excessively thin coat of it wherever you intend to paint.

The following is from VIOLIN-MAKING: AS IT WAS AND IS by E.D. Heron-Allen (Ward, Lock & Co. Limited Londan and Melbourne 1885 sec ed.)


All the data we have to go upon are the printed works of some few individuals, who have written pamphlets on the various varnishes in common use for various purposes, and it is not unreasonable to suppose that the varnish used by the luthiers or fiddle-makers, was, to a certain extent, familiar to them ; again, the reading and proper construction of these formula is rendered more difficult by the fact that many of the gums, resins, and solvents mentioned, no longer exist under the names by which they were then known, and some would seem almost entirely to have disappeared. I will now recapitulate a few of the most likely formula enumerated in these ancient brochures. The first I have been able to obtain is a treatise called "Secrets of the Arts," first published in 1550, by one Alexis, a Piedmontese. He gives the following recipes:—

1. Place some powdered benzoin (a) in a phial and cover it with two or three fingers depth of pure spirits of wine, and leave it thus for two or three days. Into this ~ phial of spirits, put five or six threads of saffron (b) whole, or roughly broken up. With this you may varnish anything a golden colour, which will glitter and last for years.

2. Take white resin (vide note ) 1 lb., plum tree gum 2 ozs., Venetian turpentine (c) 1 oz., linseed oil 2 ozs.; break up the resin and melt it. Dissolve the gum in common oil and pour it into the resin, then add the turpentine and oil, and placing it on a light fire, let it thoroughly mix; remove and keep for use; apply slightly warmed. This is a good picture varnish.

Under this head would come a kind of copal, known variously as "Indian copal," "dammar," and "gum animi," which flows from a Sumatran tree called Vateria indiccz, which was, in former times, known as "white amber" or "white resin," or "white incense," which names were also given to a mixture of oil and Grecian wax, sometimes used as a varnish.

As the names of many of these gums, etc., may be unfamiliar to lay readers, I have placed an Appendix, descriptive of them, at the end of the book (Appendix A.), and the reference letters in the text refer thereto.

D. Alexii Pedemontani de Secrets Libri Septum. (Basle, 1603.)

3. A quickly drying varnish. Take frankincense (d) and juniper gum, powder them and mix them finely. Take some Venetian turpentine, melt it in a little vessel, and add gradually, mixing thoroughly, the aforesaid powders. Filter through cloth and preserve ; apply warm, and it will dry very rapidly.

4. Take gum-mastic (e) 2 ozs., Venetian turpentine 1 oz., melt the mastic on a light fire, adding the turpentine, let it boil for some time, mixing them continuously, but not long enough for the varnish to become too thick. Put it away out of the dust. To use it, warm it in the sun and lay it on with the hand.

5. Boil 3 lbs. of linseed oil till it scorches a feather put into it, then add 8 ozs. juniper gum and 4 ozs.• aloes hepatica (~, and thoroughly mix them; filter through cloth, and before using, warm in the sun.

6. Gum-mastic 2 ozs., gum-juniper 2 ozs., linseed oil 3 ozs., spirits of wine 3 ozs., boil in a closed vessel for an hour.

The author cites as colouring matters, sandal wood (g), dragon s blood (h), madder (i) steeped in tartaric acid, log-wood (j), Brazil wood (k), all dissolved in potassa lye, and alum, and boiled. Also saffron (b), cinnabar (1), and orpunent (in). He says, "Linseed oil will dissolve mineral and vegetable colours, but kills others."

Fioravanti in a brochure called "The Universal Mirror of Arts and Sciences," published at Bologna in 1564, gives the four following formula

1. Linseed oil 4 parts, spirits of turpentine 2 pts., aloes 1 pt., juniper gum 1 pt.

2. Powder, benzoin, juniper gum, and gum-mastic, and dissolve in spirits of wine. This varnish dries at once.

3. Linseed oil 1 pt., white resin (vide note , p. 173) 3 pts., boil together, and colour as you will.

4. Linseed oil 1 pt., resin 2 pts., pine resin ~. pt., boil till it thickens. Juniper gum must never be added to the linseed oil till it boils, or else it will be burnt. The oil should be boiled till it scorches a feather dipped into it.

He gives the same directions as Alexis, as to colours, and the solvent powers of linseed oil.

Beyond these two authors, formula become rather scarce, being chiefly brought from China. All these last, and the coming, formula are not to be taken as invented at the dates given, for they are from works in the nature of Encyclopedias, and consequently post-dated.

A priest of the name of Anda, in a pamphlet entitled "Recueil abrégé des Secrets Merveilleux," published in 1663, gives the following recipe :—Oil of turpentine 2 ozs., turpentine 1 ox., juniper gum ~ dram; to be mixed over a slow fire.

One, Zahn, in 1685, in "Oculus Artiflcialis," vol. iii., p. 166, gives two recipes:—

1. Elemi(n),anime (o), white incense, and tender copal (p),

2 drains each; powder and dissolve in acetic acid in a glass vessel, adding 2 drains of gum tragacanth (q) and 4 drains crystallized sugar; dry off this mixture and powder finely. Take 1 lb. of oil of lavender (r) or turpentine and 6 ozs. Cyprian turpentine (s), and boil them on a water bath. When the turpentine is well dissolved add the powder and mix thoroughly; boil for three hours.

2. Oil of lavender 2 ozs., gum-mastic 1 oz., gum-juniper 1 ox., turpentine .~ ox.; powder the mastic and juniper, and boil the oil, then add the turpentine, and when dissolved add the powders and mix thoroughly.

The Rev. Christopher Morley in 1692, in "Collectana Chinictea Lydensia," gives under the name of "Italian varnish," the following recipe

Take 8 ozs. turpentine and boil on a fire till it evaporates down to 1 oz.; powder when cold, and dissolve in warm oil of turpentine. Filter through a cloth before use.

And, lastly, a Jesuit, named Bonanni, in his "Traité des Vernis," published at Rome in 1713, gives a list of substances used, in which lie includes—i, Gum-lac in sticks, tears, or tablets (i); 2, Sandarac (u) or juniper gum; 3, Spanish or American copal, hard and soft; 4, Amber (v); 5, Asphalte (w); 6, Calabrian resin or pitch; 7, A little-known gum which flows from the wild olive-tree, resembling red scammonmum.

Besides these he mentions as gums not used for varnishes, elemi, anime, arabic (x), pear-tree, cherry -tree, azarole—tree (vide p. 131), and other tree gums. He also alludes to gamboge (y), incense, myrrh (z), oppoponax (a a), ammonia, oils, such as turpentine, copaiba (b b), etc. It will be observed that he omits benzoin, and mistakes when he classes amongst useless gums elemi and anime, which (especially the former) are much used for violin varnishes on account of their tender qualities, otherwise his list is practicably one of the modern ingredients of varnishes for all

1 Sandarach, or rather what is sold as such, is a mixture of the resin described in note s~, Appendix A, with dammar and hard Indian copal, the place of the African sandarach being sometimes taken by true gum juniper. These gums are insoluble (or nearly so) in alcohol, and consequently the sandarach (or pouucé~ of the shops) is useless to the violin-maker. True sandarach is the pure gum of the common juniper, and appears in the form of long yellowish dusty tears, and such you must see that you get. And for this reason I have always in this chapter made use of this term gum juniper in preference to the better known term sandarach purr~,~t a. He gives many formulai, the bases of which are principally mastic, juniper gum, copal, linseed oil, and oil of lavender. It would be easy to multiply these old formula, but space forbids it; the foregoing arc doubtless the most important and useful of them, as giving us a good idea of what materials the old Cremona varnishers had at hand; their varnishes, of course, had to be most carefully suited to their peculiar requirements, and properly to ascertain this it is necessary to finc. (a) what part it plays in the construction of a fiddle, and (b) what qualities it must consequently necessarily possess. L Abbe Sibire in "La Chelonomie" thus sums up its ‘raison d étre

"IL faut que ces pates, parfaitement délayées, plus légères que massives, nourrissent los matériaUx sans masquer leur vertu, et adoucissent les sons sans les obstruer. Ce no serait pas la peine d avoir pris tant de pr~cautions avec le compas [du violon], pour les annuler avec les drogues. Emaillez tant qu il vous plaira, mais n assourdissez pas. Quand je vous commande un violon, je souhaite qu il soit joli, mais j entends qu il soit hon ; et mon oreille, indignée et jalouse, ne vous pardonnerait pas d avoir, a ses dépens, travailld pour mes yeux.

Translation of the French (" La Chelonomie " thus sums up its ' reason d ?tre " IT is necessary that this pates, perfectly diluted, lighter than massive, feeds los materials without masking their virtue, and eases sounds without blocking them. This no would be not the punishment(effort) d to have set so much percautions with the compass [of the violin], to cancel them with drugs. Enamel so much that he(it) will please you, but n dim(deafen) not. When I command(order) you a violin, I wish whether he(it) is beautiful, but j listen whether he(it) is hony and my}(Bablefish)

Before beginning to consider the matter we must get rid of all notion of colouring the wood before varnishing, or staining it with acids and other corrosives to give the appearance of age and all such inventions of the Evil one, which acids sink right into the unprotected wood as into blotting-paper, and invading the innermost heart of the fiddle~ where they have no business to be, destroy its most sovereign qualities without performing any of the proper functions of varnish. Its first and great function is, of course, the preservation of the wood without it no fiddle could attain an age of more than a very few years, and the tone would lose sweetness and power after a very short existence of harmony. On its nature also a great La1 depends: it must be tender, in a manner soft; that. ~s, it must yield to the movements of the wood, and not encase the fiddle like a film of rigid glass. It is well known that in hot weather the wood expands, and in cold weather contracts on a violin, imperceptibly perhaps, but none the less actually, and the nature and quality of the varnish must be such as to allow of its following these movements of the wood to which it is applied, without checking them in any way, as it certainly would if it were too hard. It is this that gives the oil varnishes such a vast superiority over spirit varnishes, though the former are more difficult to compound and apply, and take weeks, months (nay, years), to dry properly. Gum-lao has this same hardening effect upon varnishes, though it has been most freely and disastrously used, in the recipes given below I have specially excluded a1l such, and all spirit varnishes. To obtain this suppleness, the gums must be dissolved in some liquid not highly volatile like spirit, but one which mixes with them in substance permanently, to counteract their own extreme friability. Such are the essences of lavender, rosemary, and turpentine, combined with linseed oil.

If these conditions are borne in mind, a glance at the above formula will show that they are all adapted for application to musical instruments in a greater or lesser degree, though most of them would require, at any rate, diluting. For instance, among those of Alexis, the Piedmontese, No. 1 is hardly more than a stain, and would require the addition of gum mastic and juniper to give it consistency. No. 2 would be tender, but too heavy; the same remark applies to Nos. 3 and 4 ; they all require diluting with essence of turpentine, and so on throughout. A moment s consideration of each will suggest the dilution or alteration required to make it useful for the purposes of the fiddle-maker. Again, by a looseness of diction the old masters have been cited as covering their fiddles with an "oil-varnish," without stating whether the oil employed were an oil properly so called (as linseed oil and the like) or an essential oil (such as oil of turpentine). It has appeared in the foregoing remarks that the old varnishers used to begin by boiling their oils to an extent sufficient to render them siccative, and then after cooling they mixed in the necessary powders, having re-heated the oil to a lesser degree, otherwise the high temperature necessary to boil the oil would burn the delicate resins and gums which they~ employed. And in this they differed from the manner in which the hard glassy spirit varnishes of to-day are made.

M. Savart has made the extraordinary mistake of preferring a hard spirit varnish of gum-lao, but it is difficult to imagine by what circuitous route he can have arrived at such an erroneous conclusion. It has been said that Stradivarius and his predecessors varnished with amber, but strong evidence against this is brought by the fact, that the secret of dissolving amber and hard copal was not known until 1744, when letteis patent for the discovery were granted to one Martin. His operation was to fuse amber and hard copal by dry heat, and dissolve it in boiling oil, which was diluted with an essence raised to the same heat before it was added. This operation was, indeed, invented in 1737, but as this was the year in which Stradivarius died, he could never have used it, much less his predecessors, as stated by Otto, and besides, a varnish so compounded would be much to~ hard to use on violins for the reasons before stated.


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