Concerns about the toxicity of artists' materials have renewed interest in natural materials for fine art painting. Oil painting has long been associated with health hazards due almost entirely to using solvents in painting and cleaning. While solvents are not necessary for oil painting, many artists use solvents to change the way oil paints handle and are designed to evaporate completely as the paint dries.
Lavender or spike oil has received much attention lately and is recommended to artists as a healthier alternative to traditional solvents, such as turpentine and mineral spirits. However, many are confused by the names and the claims made by commercial firms offering these products. It is little wonder because the words lavender and spike, associated with the flowering plants in the genus Lavandula of the mint family (Lamiaceae), create as much confusion today as they have for centuries.
Origin of Words Lavender and Spike
The English word lavender is derived from the Middle English lavendre, which comes from French lavande, and from Medieval Latin lavendula, considered by some to come from Latin lividus ("bluish"). However, others believe it may have been influenced by lavare ("wash") due to the use of lavender in washing or bathing . The Romans also referred to lavender as nard, from the Latin Nardus Italica , possibly after the Syrian town Naarda near the Tigris River, considered to be the location of the modern city of Duhok, Iraq. However, Nardus was also applied to spikenard, an essential oil derived from Nardostachys jatamansi, a flowering plant of the Valerian family. The supposed similarity of the odor of lavender was likely confounded with that of spikenard . These two terms caused much confusion about which plant was referred to in classical and medieval times. Nard and spike can refer to lavender or spikenard.
Taxonomy of Lavandula
Plants in the genus Lavandula were known to the earliest botanical writers, and the first written accounts of lavender can be found in the writings of early Greek scholars such as Theophrastus (c. 370–285 B.C.). Lavandula is frequently mentioned in many herbals and botanical books, but it was not until 1780 that a detailed written study of the genus was published. De Lavandula's monograph recognized eight species and eight varieties .
The second monograph, Histoire Naturelle des Lavandes, identified twelve species along with descriptions, geographical distributions, properties, and uses. This study recognized groupings of species within the genus and continues to be a valuable work today .
When the third and most recent monograph, A Taxonomic Study of the Genus Lavandula, was published, twenty-eight species were recognized and arranged in five sections . The most recent study of the genus Lavender, The Genus Lavandula, recognizes thirty-two species described in geographic locations extending from the Canary Islands, across the Mediterranean area, North Africa, Southwest Asia, the Arabian Peninsula and Northeast Africa, and locations in India . The work by Tim Upson and Susyn Andrews, published in the book Lavender, The Genus Lavandula, describes Lavandula as having three subgenera.
Of interest in this article is the subgenus Lavandula consisting mainly of woody shrubs grown as ornamental plants and for essential oils. They naturally occur across the Mediterranean region to northeast Africa and western Arabia.
Historical Classifications of Lavender
Several species of lavender were mentioned in Roman times: Lavandula stoechas, L. pedunculata and L. dentata . Hildegard of Bingen was the first to mention L. spica and L. latifolia in her twelfth-century book, Causae et Curae . From the medieval period onwards, European species were considered two separate genera groups: Stoechas (L. stoechas, L. pedunculata, L. dentata) and Lavandula (L. spica and L. latifolia), until Linnaeus combined them. He only recognized five species in Species Plantarum (1753), L. multifida and L. dentata (Spain), and L. stoechas and L. spica from Southern Europe. L. pedunculata was included within L. stoechas .
By 1826 Frédéric Charles Jean Gingins de la Sarraz listed twelve species in three sections, and by 1848 eighteen were known .
One of the first modern major classifications was that of Dorothy Chaytor in 1937 at Kew Gardens. The six sections she proposed for twenty-eight species still left many intermediates that could not easily be assigned. Of the six sections she named, all the major cultivated and commercial forms resided in the Stoechas and Spica sections. Within the Stoechas section are L. stoechas, L. dentata, L. Viridis, and L. pedunculata, while Spica had three: L. officinalis (now L. angustifolia), L. latifolia, and L. lanata. She believed the garden varieties were hybrids between true lavender L. angustifolia and spike lavender (L. latifolia) .
One of the greatest confusions in naming lavender species occurred over the use of the name L. spica . The Swedish botanist Carl Linnaeus first used the name L. spica to include both lavender (L. angustifolia) as one variety (var. α) of L. spica and spike lavender as a second variety (L. spica var. β). Unfortunately, subsequent authors who recognized these as distinct species did not consistently use the name. Hence, L. spica was applied to both L. angustifolia and L. latifolia. With no consistency in the use of this name, the situation became completely confused, and hence the name L. spica was abandoned, the next available name being L. angustifolia Miller.
Due to this confusion, DeWolf , in his discussion of the section Spica, states that names assigned by L. vera by Augustin de Candolle  or L. ofificinalis by Dominique Chaix  should be called L. spica by Linnaeus and that the group called in the past L. spica, should be L. latifolia as named by Dominque Villars .
Despite the much-learned investigation into the identification of lavender in the writings of classical authors, it has remained impossible to unquestionably identify L. angustifolia (formerly L. officinalis Chaix and L. vera de Candolle) or L. latifolia (formerly L. spica) in historical use.
In this article, we will consider two species, L. angustifolia and L. x intermedia, principally harvested for essential oils primarily used in perfumery, food processing, cosmetics, and 'aromatherapy.'
Sources of Essential Oil
True lavender (Lavandula angustifolia)
The most common name for L. angustifolia is true lavender or English lavender (though not native to England). It is native to west Mediterranean areas extending up to 6000 feet (1800 meters) elevation. This is the source of lavender oil or true lavender oil.
Spike lavender (Lavandula latifolia)
L. latifolia is the source of spike lavender oil, similar to true lavender in appearance but flowering later. It grows naturally in Spain, with some plants growing at high and low altitudes. DeWolf says spike lavender produces the oil of spike or spike oil, which is considered inferior to lavender oil for perfumery and is used for personal care products and other uses.
Lavandin (Lavandula x. intermedia)—a hybrid of true lavender and spike lavender
Early hybrids of lavender species were cultivated at the beginning of the twentieth century and were named Lavandin, according to DeWolf. Lavandin is the hybrid of true lavender L. angustifolia and spike lavender L. latifolia. Many such hybrids are growing all over Europe and other parts of the world. Due to the larger size of these plants, the yield is much higher than other lavender species giving a more significant monetary return per acre. This long-lasting and tall-growing plant yields up to five times the essential oil as true lavender, though not as sweet smelling. Lavandin hybrids are given the taxonomic name L. x intermedia, followed by a varietal or 'fancy name.' This is the source of lavandin oil and, although considered inferior to lavender oil for perfumery has a much wider application due to its much lower cost.
Lavandin 'Grosso' (Lavandula x. intermedia 'Grosso')—a varietal of the hybrid
L. x. intermedia 'Grosso' produces the most potent fragrance among lavender plants, producing exceptionally large, deep violet flower spikes up to six inches (15 cm) long. This variety yields the most considerable amount of oil of the lavender species and is the source of essential oil.
Lavender was harvested by hand using a sickle, especially in the mountains. Now, mechanical harvesters are used, cutting up to 7,500 kilograms per day compared to 500 kilograms typical of hand harvesting. The yield of lavender oil is 40 kilograms per hectare, spike lavender oil is 50 kilograms, and lavandin oil up to 120 kilograms or more per hectare. The harvested lavender was left in the field for a few days, and then the oil was extracted by steam distillation or with carbon dioxide or other solvents .
Lavender oils are extracted from the flowers by steam distillation. Being the products of distillation, they are called 'essential oils.' Glands secrete the oils on the surfaces of the calyx or sepals of the flower. Calyx are green structures that protect the flower and its reproductive organs, which are essential to produce seeds for the perpetuation of the plant. The calyces of lavender flowers are hairy in form, providing an absorbent surface for the oil.
Modern practice using machine harvesters usually breaks the glands, so the flowers are loaded into trailers that are distilling vessels. If the herb were exposed to open air, some oil would be lost to evaporation, so the flowers are not left in the fields as when harvested by hand.
Distillation in Europe is believed to have first occurred before the sixteenth century, although there is some evidence to suggest that it was known to the Babylonians of ancient Mesopotamia. Early evidence of distillation was also found related to alchemists working in Alexandria in Roman Egypt in the first century. Alexander of Aphrodisias described the process of distilling water in about 200 AD. Distilling other liquids continued in early Byzantine Egypt under Zosimus of Panopolis in the third century. The first alembic stills were crudely represented in drawings that appear in the works of Cleopatra the Alchemist, Synesius, and Zosimos of Panopolis. Distillation was subsequently re-introduced into Europe from the Arab world around the fourteenth century.
Distillation equipment of Zosimos of Panopolis from the fifteenth century Byzantine Greek manuscript Codex Parisinus 2327 depicting an alembic still.
Lavender oil was first distilled in sixteenth-century England as part of herbal and spice mixtures. Herbs and spices were added to wine and distilled, resulting in a robust alcoholic composition .
The first stills were alembic, where flower stalks were added to water or alcohol. In modern times stills consisted of a flat bottom cylinder with a perforated bottom in which steam was fed from a boiler. Modern stills retain the cylinder configuration with a perforated grid or screen bottom or are large rectangular boxes where steam is introduced through sparge tubes along the bottom.
The still is closed and steam introduced into the vessel rises upwards through the flowers. As the introduced steam condenses on the flower surfaces, it raises the temperature causing the oil to vaporize. The oil rises and enters a condenser, which flows into a receiver-separator .
Essential Oils of Lavandula
Lavender oil: USA: CAS Number 8000-28-09; EINECS: 90063-37-9
True lavender oil from L. angustifolia is almost colorless and has a sweet, floral, herbaceous odor with a pleasant balsamic wood undertone. It has a fruity sweet top note that fades quickly, and the odor from the entire oil is not long-lasting. It is often adulterated with other natural essential oils, including lavandin oil .
Lavandin oil: USA: CAS Number 8022-15-9; EINECS: 91722-69-9
Lavandin oil was first produced in the late 1920s but has since escalated well above that of true lavender. The oil is a pale yellow to almost colorless and has the odor of clove oil, amyl salicylate, citronella, and patchouli. To stabilize the odor in perfumery, a fixative is introduced that equalizes the volatilities of the raw components in perfume oil. In perfumery, fixatives are rich, long-lasting blends that help anchor the perfume and make it longer lasting. The fixatives in lavandin are usually sesquiterpene fractions from labdanum, nitromusks, coumarin, and oakmoss .
France was one of the original producers and exporters of lavender oil to the cosmetics industry worldwide, but French lavender plantations have declined during the past century. Lavandins were first planted in the 1920s, and later, L. x. intermedia 'Abrialii,' named after Professor Abrial, who developed it in the 1930s, came into production. However, due to the incidence of a devastating disease called the 'Yellow decline,' production from this hybrid decreased. In the 1950s, a new hybrid named 'Super' was developed resistant to the 'Yellow,' and in the 1960s, another hybrid, 'Grosso,' was grown.
The chemical composition of L. angustifolia, L. x. intermedia 'Grosso' and L. latifolia extracted by steam distillation is very different, with the spike lavender oil having a much higher camphor content.
Identification of lavender oil and adulterated oil can only be detected by chemical analysis. Adulteration or dilution with fixed oils like almond oil is easily detected by putting a drop of the oil on blotting paper and looking for signs of a halo of grease remaining after a few hours. Pure essential oils evaporate entirely, so fixed oils leave any residual marks.
Composition of Lavender Oil
The typical constituents of lavender oil usually fall into the following range:
Linalyl Acetate 36.0–51%
Lavandulyl Acetate 3.4–6.2%
Linalyl acetate's content increases with the altitude at which the plants are grown .
The International Organization for Standardization (ISO) established a standard for the composition of oil of lavender, L. angustifolia (ISO 3515:2002). The composition of lavender oil includes the main components as provided in the table below:
|Component||Lavender Oil||Spike Oil||Lavandin Oil|
To meet the standard for lavandin oil (ISO 8902:2009 Oil of lavandin Grosso (L. angustifolia Miller x L. latifolia Medikus, French type), it must have a minimum linalyl acetate content of 27–37% and linalool 28–38% with camphor at 7–11%. Lavandin oil also has a variable concentration of 1,8-cineole and camphor, which is absent from oils made from L. angustifolia and provides harsher notes in the finished oil. The 'rhodinol content,' consisting of citronellol, geraniol, nerol, neryl acetate, and geranyl acetate, together amounting to a tiny percentage of the total composition, gives a sweet, rose-like odor to lavandin oil . The chemical composition of L. x. intermedia 'Grosso' varies with the method of extraction—steam-distillation and carbon dioxide extraction show differences in linalool and linalyl acetate content compared with an absolute .
Lavender oils are primarily adulterated with lavandin oil and its fractions. Other synthetic natural fractions include acetylated lavandin, synthetic linalool and linalyl acetate, fractions of ho leaf oil and rosewood oil, terpinyl propionate, isobornyl acetate, terpineol, fractions of rosemary, aspic oil, lavandin, etc. The lavender essential oil may sometimes be totally synthetic .
The scents associated with the major fractions of lavender and lavandin oil are as follows:
|Component||Scent||Also found in...|
|linalool||floral with a touch of spiciness||Mint|
|linalyl acetate||fruity odor reminiscent of bergamot mint oil||Bergamot orange|
|camphor||camphoraceous, minty phenolic, and woody||Camphor laurel|
|1,8-cineole (eucalyptol)||fresh mint and spicy cooling||Eucalyptus oil|
|β-phellandrene||peppery-minty and slightly citrusy||Canada balsam|
Spike Oil Used in Art
One of the earliest mentions of spike oil in painting was by the sixteenth-century Italian artist Gian Paolo Lomazzo. He recommended grinding colors in 'walnut oil, spike oil and other things' .
Raffaello Borghini provided a recipe for a 'varnish that dries in the shade.' The spirit varnish is made of powdered sandarac and spike oil boiled in a saucepan and applied lukewarm .
Spike oil is mentioned in remarks by Van Dyck and Rubens as recorded by Theodore Turquet de Mayerne . He recorded remarks about paintings attributed to Rubens, Van Dyck, and other artists. De Mayerne mentioned several resins for varnishes: mastic, sandarac, gum juniper, gum anime, gum lac (shellac), and benzoin. He also wrote about using several solvents, the oil of turpentine, spike lavender, and petroleum, in recipes for spirit varnishes.
Varnishes using sandarac appear in several forms in the de Mayerne manuscript, including one that instructs to dissolve sandarac in spike oil:
Twice as much spikenard oil as sandarac put in a glazed pot [on the fire] until the sandarac has dissolved and stir vigorously .
Some of the spirit varnishes included distillation products besides that from pine resin, which is the source of common turpentine. There are references from Van Dyck to distilled oil from larch resin (Venice turpentine) in the preparation of painter's varnish. According to M. K. Talley, possibly oil distilled from other conifer resins is suggested :
Il Signor Cavaliero Rubens has said it is necessary that all colours should be quickly ground and mixed with aqua di ragia (that is, with the oil which has been extracted from the soft and white resin collected from spruce fir and has good smell & through distillation with water turns a clear turpentine oil) which is better than and not as shining as spike oil .
Rubens recommended grinding pigments in turpentine before grinding in oil. For this purpose, he regarded turpentine as better and 'less fierce than lavender spike oil' . He also recommended dipping the brush in turpentine occasionally before blending the colors on the palette so that the paint was more easily worked and the colors did not 'die' or sink, 'as for blues.' Blue pigments, and in particular smalt, seem to have been perceived as a particular problem, partly because of their handling properties in oil and their tendency to sink, but also because of the danger that they would yellow .
The use of smalt in oil painting presented a particular problem due to its large particle size. Smalt having a vitreous luster , loses color as it is ground to smaller particle sizes. Smalt was never ground to small sizes to avoid further undermining its tinting strength; it is made of large, heavy particles, typically larger than 20 microns. The drawback, due to the size of the pigment particles, leading to their tendency to settle and sink in oil, is amply commented on by Charles Eastlake, who draws on the literature of art to report many expedients directed to facing this problem. One recommendation was the use of spike oil which, by speeding up the evaporation, removes the excess oil and leaves the surface matte.
Eastlake reports on Francisco Pacheco's recommendation to use spike oil with blue pigments:
Pacheco boasts that he used linseed oil with blues without fear. His method was to dip his brush occasionally in spike oil, thus causing the linseed oil to subside and producing the effect which is called (improperly as applied to the pigment) "sinking in" 
Spike oil was also used with other pigments, such as lead white. Eastlake notes this from Johannes Scheffer's painting manual of the seventeenth century:
Scheffer, in his short, but not unimportant, observations on the different vehicles for colours, says that white should be tempered with spike oil (in addition to the ordinary medium) .
Using solvents, such as spike oil, would ensure that the white paint film contained less oil so that as it dries, it would be less prone to yellowing.
Spike oil was also used in varnishes, lacquers, and japans for furniture, at least from the eighteenth century onwards. Complex recipes using spike oil alone and in conjunction with turpentine oil were used with copal, sandarac, larch resin, and gum elemi .
Both lavender oil and lavandin oil are considered to be non-toxic and have GRAS status . Considering the high usage of lavender oil on the skin in aromatherapy, the reported incidence of skin reactions is low .
Lavender oil is traditionally used and approved by the European Medicines Agency (EMA) as herbal medicine to relieve stress and anxiety. Some animal and clinical studies reveal positive results in models of anxiety and depression, although very little research has been done on molecular mechanisms. 
A report commissioned by Art Tree LLC, a supplier of spike lavender oil, determined the following:
Evidential data are supportive that Spike Lavender Oil would not cause a chronic health effect with acute or prolonged dermal or inhalation exposure. The potential for idiosyncratic allergenicity may exist and should be forewarned, but this effect would be readily identified and reversible. It is not proposed as a label caution. Adverse effects during pregnancy are unknown but assumed minimal given the history of product use. It is not proposed as a label caution. 
Spike oil naturally contains several types of substances, such as linalool (CAS No. 78-70-6), linalyl acetate (CAS No. 115-95-7), camphor (CAS No. 21368-68-3), 1,8-cineole (eucalyptol, CAS No. 470-82-6) and limonene (CAS No. 5989-27-5), that in sufficient amounts can cause acute toxicological reactions. .
As far as we know, no studies have been performed on the effects of inhaling spike oil in large amounts when used as a solvent. Most studies of the toxicity of lavender oil are in applications where exposure is minimal, such as in perfume and aromatherapy. OSHA has not established permissible levels in the workplace. This means that the effects of inhaling spike oil are unknown, so artists should take precautions and use this product with adequate ventilation and protective gear.
Where to Buy Spike Oil
Lavandin Grosso is the source of our spike oil because of its lower cost. It has a stronger scent with a slightly different note to it and is more economical than the other lavender choices. Our spike oil is imported from France, where it is extracted from the flowering tops of cultivated Lavandin (Lavandula x. intermedia var. Grosso) and steam distilled to high purity. The essential oil is completely natural with nothing added.
Bibliography and Notes
1 Russell Cross. “lavender /’lævɪnˌdə/.” The Etyman Language Blog: Adventures in Etymology and Language, May 9, 2010, Online: https://etyman.wordpress.com/2010/05/19/lavender-laev%C9%AAn%CB%8Cd%C9%99/
2 Eduard Gildemeister and Friedrich Hoffmann. The Volatile Oils, Vol. 1, 2nd edition, Edward Kremers, Trans. Schimmel & Co., New York: Wiley, 1913, p. 184.
4 J. D. Lundmark. De Lavandula, Dissertatio Academica, 1780, Upsala.
5 F. C. J. Gingins de la Sarraz. Histoire Naturelle des Lavandes, 1826, Paris.
6 D. A. Chaytor. “A Taxonomic Study of the Genus Lavandula.” Botanical Journal of the Linnean Society, Vol. 51, Issue 338, 1 November 1937, pp. 153–204. Online: https://doi.org/10.1111/j.1095-8339.1937.tb01906.x.
7 Tim Upson, “The taxonomy of the genus Lavandula L.” Lavender: The Genus Lavandula, Maria Lis-Balchin, Editor, 2003, CRC Press, pp. 11–12
8 From herein, we use the abbreviation L. to signify the genus Lavandula, as is the convention in binominal nomenclature.
9 G. P. DeWolf. “Notes on Cultivated Labiates.” 5, Lavandula, Baileya, Vol. 3, 1955, pp. 47–57.
10 Carl Linnaeus (1707–1778), also known after his ennoblement as Carl von Linné, was a Swedish botanist who wrote the first comprehensive classification of plants, Species Plantarum, 1753.
11 Maria Lis-Balchin. “History of Nomenclature of Lavandula Species, Hybrids and Cultivars.” Lavender: The Genus Lavandula, 2003, CRC Press, pp. 51–52.
12 D. A. Chaytor. “A Taxonomic Study of the Genus Lavandula.” Botanical Journal of the Linnean Society, vol. 51, Issue 338, 1 November 1937, pp. 153–204. Online: https://doi.org/10.1111/j.1095-8339.1937.tb01906.x.
13 M. L. Green. “Botanical Names of Lavender and Spike.” Bulletin of Miscellaneous Information (Royal Botanic Gardens, Kew), vol. 1932, no. 6, 1932, pp. 295–297. Online: JSTOR, www.jstor.org/stable/4113442.
14 G. P. DeWolf. “Notes on Cultivated Labiates.” 5, Lavandula, Baileya, Vol. 3, 1955, pp. 47–57.
15 Augustin Pyramus de Candolle (1778–1841) was a Swiss botanist who originated the idea of “Nature’s war,” which influenced Charles Darwin and the theory of natural selection.
16 Dominique Chaix (1730–1799) was a French botanist and priest of Les Baux, a hamlet of La Roche-des-Arnauds, in the Hautes-Alpes.
17 Dominique Villars or Villar was an eighteenth-century French botanist whose main work Histoire des plantes du Dauphiné was published between 1786 and 1789.
18 Maria Lis-Balchin. “History of Nomenclature of Lavandula Species, Hybrids and Cultivars.” Lavender: The Genus Lavandula, 2003, CRC Press, p. 55.
19 Jo Castel and Maria Lis-Balchin. “History of Usage of Lavandula Species.” Lavender: The Genus Lavandula, 2003, CRC Press, p. 46.
20 E. F. K. Denny. Field Distillation for Herbaceous Oils, 3rd edition, 2001, Denny, McKenzie Associates, PO Box 42, Lilydale, Tasmania 7268, Australia, E-mail: mailto:[email protected].
21 Steffen Arctander. Perfume and Flavor Materials of Natural Origin, 1960, p. 254.
23 Aqua Oleum. The Essential Oil Catalogue, 1993, Gloucestershire, UK: Stroud.
24 Maria Lis-Balchin. “Lavender.” Handbook of Herbs and Spices, Vol. 2, 2004, CRC Press, pp. 179–195.
25 R. Pellerin. “Supercritical fluid extraction of natural raw materials for the flavor and fragrance industry.” Perfumer & Flavorist, 1991, 16(4), pp. 37–39.
26 Maria Lis-Balchin. Aroma Science: The Chemistry and Bioactivity of Essential Oils, 1995, Amberwood Pub. Ltd., Surrey.
27 “…mediante i colori macinati con oglio di noce e di spica e d’altre cose.” Gian Paolo Lomazzo. Della forma delle Muse, Milano, 1591, p. 302.
28 “La vernice che secca all’ombra altresì in due modi si può fare: predansi per lo primo un’oncia d’olio di spigo e un’oncia di sandracca in polvere o vero vernice grossa e, mescolate queste cose insieme, si facciano bollire in pentolino vertiato nuovo; e chi volesse di più lustro vi metta più sandracca en mentre bolle si mescoli benissimo et essendo ben disfatta si levi dal fuoco, e come é tiepida con diligenza si metta in opera, che questa é vernice molto gentile et odorifera.” Raffaello Borghini. Il riposo di Raffaello Borghini,  Fondo Cicognara (Biblioteca apostolica vaticana), Nestenus M , Moücke F., 1730, pp. 221–222.
29 Théodore Turquet de Mayerne (1573–1655) was a Genevan-born physician who treated kings of France and England and advanced the theories of Paracelsus. De Mayerne compiled the so-called ‘de Mayerne manuscript’ between 1620 and 1646 based on conversations with painters. The manuscript includes contributions from Rubens, van Dyck, Mytens, Paul van Somer, and Cornelius Johnson.
30 Donald Fels erroneously uses the term spikenard oil to mean spike oil and to distinguish it from lavender oil in other parts of his translation of the de Mayerne manuscript. Donald C. Fels, Jr. Lost Secrets of Flemish Painting, Revised Edition, Eijdsen, Netherlands: Alchemist Publications, 2010, p. 24.
31 Mansfield Kirby Talley. Portrait Painting in England: Studies in the technical literature before 1700, Paul Mellon Centre for Studies in British Art, 1981.
32 J. A. van de Graaf, “Het de Mayerne Manuscript als bron voor de schildertechniek van de Barok” (dissertation), Utrecht, 1958, Entry no. 122.
33 Jo Kirby. “The Painter’s Trade in the Seventeenth Century: Theory and Practice.” In National Gallery Technical Bulletin, Vol. 20, 1999: Painting in Antwerp and London: Rubens and Van Dyck, p. 15.
34 Van de Graaf, 1958, nos. 121–2, pp. 190–1, cited above in 32. From T. Turquet de Mayerne, ‘Pictoria, Sculptoria, Tinctoria et quae subalternarum artium spectantia...,’ 1620–46, British Library MS Sloane 2052. The earliest complete transcription was published by Ernst Berger in 1901: E. Berger, ‘Quellen für Maltechnik während der Renaissance deren Folgezeit (XVI-XVIII. Jahrhundert’), Munich, 1901 (Beiträge zur Entwicklungsgeschichte der Maltechnik, IV).
35 The term vitreous (derived from the Latin for glass, vitrum) refers to a glassy luster. Lustre or luster is how light interacts with the surface of a crystal, rock, or mineral. Vitreous luster commonly occurs in transparent or translucent minerals with relatively low refractive indices. The low refractive index of smalt makes this pigment very transparent with little tinting strength, especially in oil paint, so that the color of oil often causes it to yellow or darken as the oil ages.
36 “I no tengo por malo mojarel pincel en el [azeite] de Espliego cuando se va pintando, porque ayuda a rebeverse.” Francisco Pacheco. Arte de la Pintura: su antiguedad y grandezas, etc., Simon Faxardo, 1649, p. 392. See also “The Art of Painting” (Lisbon, 1649) in Zahira Veliz. Artists’ Techniques in Golden Age Spain, Cambridge, 1987. Charles Eastlake. Materials for a History of Oil Painting, Vol. 1, London: Longman, Brown, Green, and Longmans, 1847, p. 431.
37 “Cerussam spicae oleo temperare melius putatur.”—Johannes Scheffer. Joannis Schefferi Argentoratensis Graphice, id est, de Arte de Pingendi, liber singularis, Norimbergæ Officina Endteriana, 1669, p. 179. Charles Eastlake. Materials for a History of Oil Painting, Vol. 1, London: Longman, Brown, Green, and Longmans, 1847, p. 431.
38 Marianne Webb. Lacquer: Technology and Conservation, Butterworth-Heinemann, 2000, p. 125. See also Christopher Augerson. “Copal Varnishes Used on 18th and 19th Century Carriages.” Journal of the American Institute for Conservation, Vol. 50, No. 1 (Spring / Summer 2011), pp. 14–34.
39 GRAS status is a regulatory designation first introduced by the US Food and Drug Administration (FDA) as part of the 1985 Food Additives Amendment to the Federal Food, Drug, and Cosmetic Act (FD&C Act). Its purpose was to exempt certain food ingredients from the definition of food additives.
40 Robert Tisserand, Rodney Young. Essential Oil Safety—E-Book: A Guide for Health Care Professionals, 2nd Edition, revised, Elsevier Health Sciences, 2013, pp. 324–328.
41 Victor López, et al. “Exploring Pharmacological Mechanisms of Lavender (Lavandula angustifolia) Essential Oil on Central Nervous System Targets.” Frontiers in Pharmacology, Vol. 8 280, May 19, 2017, doi:10.3389/fphar.2017.00280
42 Daniel E. McLain. Chronic Health Effects Assessment of Spike Lavender Oil, Walker Downey & Associates, Inc., 2009, p. 5. Online: https://arttreehouse.com/artstore/PDF/Health-Effects-Assessment-of-Spike-Lavender-Oil.pdf
43 Safety Data Sheet: Lavandin Oil Grosso Spain. Online: http://www.indukern-ffingredients.com/c/portal/security-sheet?idProduct=000000000006110514&language=E&country=UK&title=LAVANDIN%20OIL%20GROSSO%20SPAIN