Classic Violin Varnish
Ground
It is true that violin makers will talk all day long about their varnish, on the other hand, it is very difficult to get them to talk about their ground. The concept is this—like primer is to paint, ground is to varnish (see last photo on this page.) Of course it can be more complicated then this basic concept. For example, some look for a primer and sealer before the ground is applied. It is dependent on your objective and the entire varnish package start to finish. Experience is your best teacher. There is nothing easy about varnishing in the traditional sense. They say you will begin to learn violn making in the first ten years, and then spend the rest of your life learning about varnish.
Basicly two main types of varnish: Resin/Oil and Spirit (alcohol based)
For violin varnish, linseed oil and walnut oil are most often used in combination with resins. The oil is prepared by cooking or by exposing to air and sunlight. The resin is typically available as a solid, and is then "run" by cooking or literally melting it in a pot over heat without solvents. The thickened oil and prepared resin are then cooked together and thinned with turpentine into a brushable varnish.
Resin
Most resin or "gum" varnishes consist of a natural, plant- or insect-derived substance dissolved in a solvent. The two main types of natural
varnishes are spirit varnish (alcohol-based) and turpentine or petroleum-based varnish. Some resins are soluble in both alcohol
and turpentine. The resins include amber,
dammar, copal, pine resin, sandarac, balsam, and shellac. Over centuries, many recipes were developed which involved the combination of
resins, oils, and other ingredients. Ground and varnish layers impart special tonal qualities to musical instruments and thus are
sometimes regarded as carefully guarded secrets. The interaction of different ingredients is sometimes difficult to predict or reproduce; this is the territory of the violin maker.
The word varnish derived ultimately via ancient Greek from a place name of a city in ancient Libya, where resins from the trees of once existing forests were sold.
In modern English the ancient city is referred to as Berenice; otherwise the existing city in modern Libya is called Benghazi.
Drying oil
There are many types of drying oils, including linseed oil, tung oil, and walnut oil. These contain high levels of polyunsaturated fatty acids.
Turpentine or solvent
Traditionally, pure gum turpentine is used as the thinner or solvent.
Alcohol based-varnish
Shellac
Shellac is a very widely used single component resin varnish that is alcohol soluble. The source of shellac resin is a brittle or flaky secretion of the female lac insect, Coccus
lacca, found in the forests of Assam and Thailand, and harvested from the bark of trees where deposits provide a sticky hold on the
trunk. Shellac is the basis of French polish, a technique that produces an inimitable sheen. Specified "dewaxed" shellac has been processed to remove the waxy substances from the raw shellac.
Shellac varnish is typically available in a variety of colors from clear to amber/orange/ruby varieties.
Procedure:
- Preparation of wood surface
- Ground layer, mineral or otherwise (like a primer/sealer coat). One traditional ground "vernice bianca" composed of egg white, gum Arabic or cherry gum, candied sugar, and honey.
- Color coats: washes/glazes/lakes
- Top coats: colored or clear
Investigative photos-
Ground layers and varnish influence the acoustical outcome of the finished violin.
A unique polarized light microscopy; cross section Scanning Electron Microscopy
Stradivari varnish (color layers and dispersed minerals 10,000x magnification / Stradivari varnish.
visible within the varnish) wood-surface side on left
(photos courtsey of RobertMuggli/McCroneAssociates JournalofEducationinChemistry,July05)
light microscopy of red pigment in situ violin varnish, Stradivari 1724
(photo courtesy of JPEchard, laboratory of the MuseumofMusic Paris 2006)
Scanning electron micrograph showing wood, graphic illustration of photo on left
ground layer and varnish.
SEM Stradivari sample: Pozzolana particles on spruce, X-section endgrain.
wood, ground and thin varnish layer.(four photos courtsey of JCAS/Barlow/Woodhouse1989)
Chemical analysis of ground layer in 7 varnish samples, (chart numbers are relative percentages.)
(chemical analysis courtsey of JCAS/Barlow/Woodhouse1989)
A fossil gum or resin principally found along the shores of a large part of the Baltic and North Seas, especially
off the promontory of Samland. It is cast up by the sea, and collected at ebb tide with nets, and is also brought
up by divers and dredging. It is partly soluble in alcohol and entirely so in chloroform. It decomposes when heated
below 300 degrees Celsius, yielding "oil of amber," and a black residue called "amber pitch."
This last, when dissolved in oil of turpentine or linseed oil, forms "amber varnish" or "amber lac."
(1) A balsamic resin obtained from Styrax benzoin, a tree native to Java and Sumatra, and from
other varieties of the Styrax;
The red wood of the Brazilian Caesalpina used as a dye. The dark, yellowish-red heartwood of the Caesalpina
echinata or Pernambuco wood (bois de Fernambuc) is largely used for the making of violin bows. 
An ore of mercury, cochineal-red to lead-gray mercury sulphide, found in crystals and powders, and used as
a pigment. Cinnabar is usually found in a massive or granular form but can also occur as small crystals.
The main areas for cinnabar mining are in Italy and Spain.
A dyestuff consisting of female cochineal insects, killed and dried by heat, which gives a brilliant scarlet
dye and the pigment carmine. 
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.
as well as from Brazil and other South American countries, from trees of
the Guibourtia, Trachylobium and Hymenia families.
The raw copal yielded
by Zanzibar Trachylobium hornemannianum is 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 indica is also known as gum anime, and is often confused with true copal
in commerce.
Singapore damar
The best gum dragon or dragon's blood is obtained from the Calamus draco, a rotang or mattan palm
of the eastern archipelago and India. It is a dark red-brown in color, brittle, nearly opaque, and when ground,
supplies a fine red powder soluble in ether, alcohol, and fixed and volatile oils. Much of the dragon's blood of
commerce is obtained from the Pterocarpus draco of South America.
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.
Also known as (Gum Gutta or Gummi Gutti) **Poison**.
Externally a dirty orange in color, gamboge, which occurs in commerce as pipe or roll gamboge, which is purer,
and cake gamboge, inferior in quality, is a gum resin coming from Cambodia and Thailand. It is tasteless, hard and
brittle, affording a brilliant yellow powder, and is often adulterated with rice powder or pulverized bark.
This is a resinous encrustation formed of the twigs of various trees by an infesting insect, the Coccus
lacca, allied to the cochineal insect in the East Indies and southeastern Asia. To obtain the largest
amount of both resin and red dyestuff, which is segregated in the ovaries of the females, the twigs with their
living inhabitants are gathered in June and November. "Stick lac" is the lac encrusting the twigs when
gathered; the resin is crushed small and washed in hot water to free it from coloring matter known as "seed
lac," and this, melted and strained is the "shellac" of commerce. Lac forms the basis of some of
the most valuable varnishes.
The Mexican and Central American Haematoxylon campechianum supplies the dark red heartwood, whose
color pigments readily dissolve in boiling water. It is also known as campeche wood. 
The Dutch Rubia tinctorum is the plant whose peeled roots supply madder, a pigment whose coloring
principle is alizarin. The madders are brown, madder carmine and madder orange in color. 
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.
A fine, sandy volcanic ash, originally discovered and dug in Italy at Pozzuoli
in the region around Vesuvius, but later at a number of other sites.
It is found in all the volcanic areas of Italy in various colors:
black, white, grey and red. Pozzolana is a siliceous and aluminous material which reacts with calcium hydroxide in
the presence of water to form
compounds possessing cement like properties. Much speculation and research into the native
Italian volcanic ash as a possible source
for the mineral-laden ground layer on some classic Italian violins.
The dried, deep orange-coloured stigmas of the saffron plant, Crocus sativus, which yield a much used
pigment for coloring varnishes. 
This wood, much used as a dye, is not the Santalum yasi, but the Pterocarpus santalunis,
and grows in India and Ceylon. The close grained heartwood is a dark red in color. 
This is a yellowish, transparent resin obtained from the Callitris quadrivalvis, a conifer of northwest
Africa; analogous resins coming from the Callitris sineusis of China and the C. reessii of South
Australia,
which is known as pine gum. Sandarac reaches commerce in the form of small round balls
or elongated tears, is yellow in color, and somewhat harder than mastic for which it is sometimes substituted.
True Sandarac is obtained from the common juniper, and is another name for juniper gum.
