Painting Mediums

RESIN: any of a class of nonvolatile (non evaporating), solid or semisolid organic substances obtained directly from certain plants as exudations or prepared by polymerization of simple molecules: used in medicine and in the making of varnishes and plastics. A substance of this type obtained from certain pines; rosin.


Hard Resins: Fossil Resins

Tend to darken and crack with age. Must be boiled in oil to form a varnish; the use of boiled oil mediums has led to a considerable deterioration of the paintings executed in them and it is recommended that they be avoided by artists, though their popularity is returning in attempts to recapture the glass like layering of past paintings.

Amber: other names: berenice, verenice, vernix, glessum (glas or glassa). a pale yellow, sometimes reddish or brownish, fossil resin, translucent, brittle and capable of gaining a negative electrical charge by friction. It comes chiefly from the resins of pine trees that grew in northern Europe. These resins were gummy materials mixed with oils in the trees. When the oils became oxidized, hard resins were left. These pine trees were buried underground or underwater, and the resins slowly changed into irregularly shaped lumps of amber. The largest supply of amber lies in the Baltic Sea area. It comes from a species of pine tree that is now extinct. Some experts consider this amber the only true amber. Central America has important deposits of amber from other sources. Most amber is mined from a claylike soil called blue earth and was thought by the early Greeks to be a mineral.



Copal: a hard, lustrous resin obtained from various tropical trees, it has the same recommendations as amber and nearly the same defects. The best Copal is said by Eastlake to come from South-Africa and were imported into Europe through India. The Hard Copal resins today come from Sierra Leone or Zanzibar. The general argument against copal, as with other resins, is its reported tendency to darken and crack. However, artist/investigators of this medium such as Melville Holmes argue that good quality copal mixed as no more than 25% of the medium with a drying oil (linseed or nut) produces a good quality paint film with no proven and documented signs of extreme yellowing or cracking (as opposed to normal craquelure). Mixed in small quantities with oil it promotes the flow of the paint and gives a painting lustre and brilliance, but this resin is too brittle to be used as a varnish thinned only with Turpentine, and in its hard (semi-fossil) form is insoluble when dry. While this insolubility makes the resin an improper choice for a final varnish, it is precisely this feature which makes it desireable as an additive in medium. The old "No.1 Water-white transparent" congo copal was best used, but is no longer in production since the Belgians were driven from the Congo in the 1960s, making the procurement of measured quality copal difficult to come by. The term copal refers to a number of resins, from different botanical origins and chemical constitutions, from both living (soft resin) and hard or semi hard (fossilized) sources. Therefore, copal mediums purchased ready-made may contain unknown and variable qualities of resin, making them susceptible to the darkening and cracking of which they have often been accused.

Soft Resins: Recent Resins

Extruded from live plants. Dissolved in cold diluent. Resoluble.

Soft Copal: Milan resin tapped from live trees can be dissolved in alcohol. Many varieties exist of differing grades. Unlike its fossil counterpart, soft resin is resoluble, therefore causing the same concerns as any resoluble resin when used as an ingredient in painting medium.

Sandarac: other names: red varnish, vernix, common glas. Resin from the African arbor vitae, known as Thuja articulata, similar to the Juniper and often referred to by that name. It is of lower quality than amber or copal for making varnish.

Mastic: also known as white varnish. An aromatic, astringent resin obtained from a small anarcadiaceous evergreen tree native to the Mediterranean region. Believed to have been the resin that replaced Amber in the European's thick medium, known as Megilpe, which was mixed with boiled linseed and litharge (huile grasse). It darkens and is more brittle than dammar which has replaced it for creating essential oil varnishes as well as in mediums.

Resin of Turpentine: also known as glorie, white resin, colophone, or concrete turpentine. Is said to be clear and not to yellow over time. This resin in only available as dark rosin for wood varnish today, and not recommended for fine art. see oleoresin below.

Dammar: a soft resin derived largely from dipterocarpaceous trees of southern Asia and used for making colorless varnish. Any of various similar resins from trees of other families. Due to its colorless nature and the fact that it does not harden and crack as badly as the above listed resins, it has become the preferred resin for oil painting in the 20th century. It is mixed with oil of Turpentine to create an essential oil varnish. And when the dried varnish becomes soiled on the surface of the painting over time, it can be removed again with the same essential oil of Turpentine. However, dammar becomes less soluble with age so strong solvents may be needed for its removal when aged. Modern writer Melville Holmes states that "Mastic and Dammar have been studied in considerable detail by conservation scientists because of their use as picture varnishes and their relatively rapid darkening is well documented." I have not found statements claiming such darkening takes place when dammar is incorporated into an oil medium.

OLEORESIN: a mixture of an essential oil and a resin, found in nature.

Examples:

Common Turpentine: any of various oleoresins derived from coniferous trees, esp. the longleaf pine, and yielding a volatile (one that readily evaporates) oil [essential oil of Turpentine] and a resin [concrete Turpentine or rosin] when distilled. Rosin is considered an adulterant in modern painting mediums.

BALSAMS: A turbid, viscid (sticky) , water-insoluble liquid resin. Any of certain transparent turpentines.

Venice Turpentine: obtained from the larch Larix Europea or Larix decidua, this is a viscous yellow liquid from which resin acids cannot be crystallized and in this respect it differs from common turpentine. It is soluble in alcohol, ether, acetone and turpentine but only partly soluble in petroleum hydrocarbons. When purified, it no longer shows its natural tendency to darken a painting and produce cracks, but is very cohesive mixed with a fixed oil. It should be used sparingly since it is resoluble, but a little is all that is usually needed to create the desired effect of glassy sheen. It was the most common varnish found in early recipe books and had been commonly used in Europe at least from the time of Rubens.

The French called it Thérébenthine de Venise and said that it flowed without an incision from conifers (meleses, pins, sapins). They said it was a golden liquid, clear as water which thickens with age turning lemon yellow. However, in the 17th century, common pine turpentine (rosin) was often sold as Venetian turpentine. "Large quantities were sold with water on the top to mask the (inferior) reddish liquid below." True Venetian Turpentine is only from the larch tree.

Strasbourg Turpentine: From the white fir abies pectinata, this is paler than Venice turpentine and very difficult to obtain. Seventeenth-century compilers of recipes were unanimous in preferring Strasbourg turpentine over Venice turpentine due to its better color and odor. But both dry into desirable film when mixed with drying oils, etc.; compared with the customary oils and varnishes, they are acceptably permanent, nonyellowing, and durable, and tend to impart more flexibility and life to the films than do most resins.

***When Venice or Strasbourg turpentine is mixed with stand oil, the resulting varnish is superior for artists' mediums to the cooked oil-resin varnish group; and when liquid driers are added, the resulting product is superior to those varnishes into which driers have been cooked.

Canada Balsam: Said to resemble Strasbourg turpentine, Canada balsam is relatively pure and valuable for its transparency and its high refractive index. It is usually more expensive than Strasbourg and has been less tested.

Copaiba Balsam: of variable composition and viscosity, Copaiba balsam was found to be impossible to remove completely and to display excessive darkening and shrinkage. It is now avoided in picture making.

ESSENTIAL OIL: any of a class of volatile oils obtained from plants and possessing the odor and other characteristic properties of the plant: used chiefly in the manufacture of perfumes, flavors, and pharmaceuticals.

Examples in Painting:

Oil of Turpentine: colorless, flammable, and volatile, having a penetrating odor and a pungent, bitter taste. Used in essential oil varnishes where it gives a matt finish, and for thinning paints and cleaning brushes. The overuse of spirit of turpentine in thinning oil paint will make them appear flat and dull and, reducing the binding medium, can cause flaking due to lack of adhesion.

Spike Lavender Oil: The oil of the Lavender plant, Lavendula latifolia, it can be used in the same ways as oil of Turpentine, but dries more slowly. Has a "pungent odour" stronger than turpentine. Can be used to retard the drying of oils but "it is generally felt that they do the paint films no good," according to one writer. He may, however, have been using the oil of the female plant, known as lavenda vera, which has a stronger odour and is used in perfumes. For painting one should use the less aromatic oil of the male lavendula spica.

MINERAL DISTILLATIONS

Naptha: Any of various liquids composed only of hydrogen and carbon that boil below 450 degrees F. which are distilled from other products. Unlike the essential oils listed above, this diluent is distilled from a mineral rather than a plant. The danger is in its low flash point, between 20 and50 degrees F, making turpentine the preferred solvent in modern painting.

Naptha (or Naphtha) can be made when coal tar [the pitch used by early shipbuilders to waterproof their vessels], a sticky substance made from soft coal, is distilled. It was the first volatile oil used to dissolve resins for varnish and considered the purest and most unchanging diluent.

In todays terminology solvent naphtha refers to a rather impure by-product of coal tar distillation belonging to the benzol group. It is a good solvent for coal tar and some asphalts, but is a poor general solvent for paint and varnish materials. It is sometimes useful for this reason, as it has little effect upon the oils and resins in an oil painting and may be used to wash off superficial dirt, wax, etc., without the film's being affected.

V.M.&P. Naphtha (Varnish Makers and Painters Naphtha) is a modern variety of petroleum distillate intermediate between mineral spirits and gasoline. With a lower flash point, a higher rate of evaporation, and usually a more disagreeable pungent odor it is not so well suited to paint purposes as is mineral spirits.

Mineral Spirits are a petroleum distillate intermediate between Kerosene and Gasolene (petrol) with properties similar to those of turpentine when used as a paint thinner. It has several advantages: it leaves no sticky, gummy (resin) residue upon evaporation, it does not deteriorate with age, its price is a small fraction of that of gum turpentine, and it is less likely to affect persons prone to allergic reactions. It can replace turpentine in most studio uses except in dissolving dammar.

VARNISH: a preparation for finishing or coating wood, cloth, or other materials, consisting of resinous matter, as copal or lac, dissolved in an oil, alcohol, or other volatile liquid. In contemporary use, the sap of certain trees used for the same purpose.

OLEORESINOUS VARNISHES:

When used in this way, oleoresinous refers to a resin dissolved by heating into a drying oil such as linseed or walnut oil to create a thick liquid varnish.

Amber and Copal varnishes turn very dark and are red to begin with. Sandarac has the same quality, with all eventually drying and cracking to the point of disintegration, though Sandarac is worse than either Amber or Copal. They are all thick, dark, and slow drying. Florentine and Sienese schools used a green underpainting in their skin tones which, when varnished with one of these red varnishes, was neutralized, giving a proper effect to the skin color.

Mastic and Concrete Turpentine (colophone) are clearer in color, but still tend to crack over time.

Vernice Liquida: from Berenice (amber), the constellation of Berenice's (golden) hair. Nero referred to the golden tresses of his empress, Poppoea and Pliny observed that, because of Poppoea, amber-colored hair became fashionable. A varnish of the middle ages made with Amber (or Sandarac) heated and mixed with drying oil. As defined by Cardanus: "The juice which flows from the Juniper (Thuja) is called vernix. -- From dry vernix and linseed oil, liquid vernix is made: this is calculated to resist all effects of the atmosphere, and therefore is applied to pictures."

Early Recipe for a thick Vernice Liquida: 3 parts linseed, 1 pt. Sandarac or Amber, and sometimes (the white resin) concrete Turpentine was added in 2 or 3 parts. The concrete Turpentine aids in the liquefaction of the Sandarac making the varnish lighter and adds gloss. The recipe with Sandarac is called common vernice liquida, while that with amber is vernice liquida e gentile. With the glossy turpentine (rosin) added, it was especially prized for varnishing cross bows and furniture.

ESSENTIAL OIL VARNISH: a resin or balsam dissolved in a volatile oil. Not til the close of the 15th or beginning of the 16th century did painters use an essential oil varnish.

Examples of Varnish:

Italian Varnish: essential oil and balsam, sometimes with a resin added. Another recipe used clear (silver) fir Turpentine (resin) mixed with an equal part naptha. It was applied warm and is a thin, but glossy varnish.

Flemish Varnish: the Flemish sometimes used "the clearest Venice Turpentine boiled with an equal quantity of essential oil of Turpentine." It protects from the effects of air and moisture and can be painted over. Vandyck used 2 parts Turpentine to 1 part Venice Turpentine boiled as before and applied cool. Do not allow the essential oil to evaporate or the Venice will not dry well and becomes too thick. This was considered ordinary painters varnish. A retouch varnish used between layers to "oil out the colours" was made of "essential oil of Turpentine, Spike Oil, or (naptha) Petroleum, with (white resin of) Turpentine itself, dries at last and prevents the varnish from cracking. Note: very little is necessary; the tenth or twelfth part." (ratio of essential oil to resin = 10:1 or 12:1) -De Mayerne

This thin resinous film does not yellow, "undergoes no alteration... leaves a comparatively fresh surface which takes the colour easily; and, having scarcely any body, does not affect the superadded tints." Best used as a retouch varnish between layers to oil out the color.

Varnish sold by Pomet in 17th century France:

1.) Spike oil, Venetian Turpentine, and Sandarac melted together to produce a siccative varnish.

2.) Venetian varnish or White varnish -

spirits of Turpentine, Venetian Turpentine and Mastic melted together.

3.) Spirit varnish of Sandarac, Amber, Gum Elemi and Mastic with Alcohol.

4.) Common varnish - resin of Turpentine (rosin/colophone) melted with Spirit of Turpentine

Some of the earliest recipes for varnish were for Venetian varnish, used to varnish and paint engravings.

De La Fontaine's recipe for Venetian Varnish, which was used to coat paintings, mixed 1 oz. of Venetian Turpentine with 1/2 oz. of spirits of Turpentine and boiled in a water bath until the balsam melted. Allow to cool - but warm slightly to increase flow before applying. Other recipes from the period are similar, though some incorporate mastic.

A mixture of mastic ground with linseed oil could be used to grind colours which would be more resistant to the air.

Le Blond de la Tour complained that all varnishes of his day yellowed.

Modern Varnish: A retouch varnish can be made by mixing liquid Dammar varnish with Rectified Turpentine in a ratio of 1:2. While a final varnish can be made by mixing the same ingredients in a ratio of 2:1 or as much as 4:1. Brush on with a flat 2" wide hogs hair bristle brush. This is the preferred artists' picture varnish for the reasons listed above, under Resins: Dammar.

See Discussion with National Gallery Conservator

MODERN VARNISHES

Other modern varnishes used primarily for woodworking and industrial purposes are made using Lac, a resinous substance deposited on the twigs of various trees in southern Asia by the female of the Lac insect. Shellac is lac that has been purified and formed into thin sheets, used for making varnish, or a varnish made by dissolving this material in alcohol or a similar solvent.

Shellac tends to turn dark and to crack with age and is therefore not to be used as a retouch or final varnish. But White or Orange grade Shellac can be thinned with alcohol to a watery consistency to be applied as an isolating varnish, or thin size, over a preliminary oil wash underpainting. The alcohol used should be ethyl, or grain, alcohol. Pure Grain Alcohol is 94% pure alcohol and 6% water, while Anhydrous or Absolute Ethyl Alcohol is 100% alcohol. Either will work to mix an extremely thin solution of shellac that can be used as a sizing for porous surfaces and as an isolating layer between films of paint in tempera painting. Or it can be applied just thickly enough over a wash drawing or underpainting in oils to seal the image, make the surface less absorbent and give it tooth for the adhesion of the body painting over it. Since it is not soluble in turpentine or mineral spirits it can protect a paint layer from further solvents in the overpainting. The drawback is that alcohol (shellac's solvent) can have a destructive effect on oil paint layers and, after the alcohol has evaporated, any layer of shellac must be completely covered in pigmented layers which may be contrary to the desired effect in the painting. Perhaps a safer and more flexible method is to seal an ink drawing on gesso with a glue size or to add a thin coat of damar retouch varnish between layers on canvas.

Lacquer: a protective coating consisting of a resin, cellulose ester, or both, dissolved in a volatile solvent, sometimes with pigment added. Any of various resinous varnishes, esp. one obtained from a Japanese tree, Rhus verniciflua, used to produce a highly polished, lustrous surface on wood or the like.

Ester: a compound produced by the reaction between an acid and an alcohol with the elimination of a molecule of water, as ethyl acetate or dimethyl sulfate.

Cellulose: an inert carbohydrate, the chief constituent of the cell walls of plants, wood, cotton, hemp, paper, etc.

SYNTHETICS

Pure Methacrylate, or acrylic, solution in mineral spirits has been accepted by museum and technical specialists since the early 1930s. It is colorless and dries to a dull satiny finish, often preferred to the higher gloss of damar. This is best used on light colored, or "blonde", works of art since dark pictures may be made to look grayish by matt varnishes. Acrylic's great flexibility may allow it to be applied to paintings that have not cured if a work must be shipped out of the studio prematurely.

A pure solution of Polycyclohexanone (keytone) in mineral spirits may be better suited for dark images as it dries very closely to the gloss of damar and has been used since the 1950s.

These are best used as final varnishes on oil paintings since they can be easily removed with mineral spirits. One disadvantage of the synthetic varnishes is their tendency to form films that are softer, with tendencies to attract dirt and dust to a greater extent than damar, thus potentially requiring more frequent cleaning. And their softer films may not protect the painting surface from abuse and scratches as well as the harder damar.

Gamvar: Gamblin Paint Company has developed a synthetic varnish in cooperation with the National Gallery that can be thinned with Odorless Mineral Spirits (such as their Gamsol) and applied to oil and acrylic paintings. The varnish is low odor, dries quickly and has a beautiful even sheen. Gamvar can now be purchased in a premixed 5.4 oz. or 2 oz. bottle. I highly recommend this varnish as a modern replacement to Damar, which I have used for many years.

See Discussion with National Gallery Conservator

3 Things A Painting Can't Live Without

In Vermeer's Woman with a Scale, the focal point
of the painting is accentuated with nothing more

than a glance and delicate hand position.

In Picasso's portrait of Gertrude Stein,
the colors are muted but quite varied
and establish an introspective mood.

Good painters don’t merely re-create what is in front of them. An experienced artist knows how to create a successful painting no matter what situation or model he or she is presented with. Of course, this often comes after years of practice and experimentation—as well as the development of a unique artistic voice—but there are some basic characteristics that all good paintings have in common.

1. A strong focal point. A focal point is not like the big bold ‘X’ that marks the spot on a treasure map. It can take on any shape and size. It can be bold but it can also be subtle. A dappling of light, a pop of color, an expression or emphatic gesture—any of these can become a focal point in a composition. Regardless of how it is created, its purpose should be to engage the viewer or act as the culmination of the momentum built in the work.

2. Layers of color. Color makes a painting tranquil or vibrant, dramatic or stark, and this comes about not only in color choices, but how you build passages of color over one another or side by side. Warm and cool colors in a sky create a sense of atmosphere and space more than any one swath of color, no matter how perfectly matched it is to the sky above.

3. Changes in direction. In many great paintings the image is realistically rendered, but brushstrokes are clearly visible; you are aware of how the painting is painted. Think about how the paint application of Jan van Eyck versus Vincent van Gogh perfectly reflects or resonates with what the artists painted. The way a brush moves paint around makes a statement that should be taken advantage of. You can start by being mindful to changes in the direction of your brush, literally working on a painting with different strokes and from various angles.
When you look at works of art that you respond to, always ask yourself why. Keep those characteristics in mind as you develop your own pieces, too. That awareness is what drives the instruction that American Artist delivers. Whether it’s a calendar featuring intriguing and unique works of art that make you think; DVDs such as Mastering Portrait Drawing, that delve into the details of how to draw a person’s likeness; or magazines like Studios, where you get a peek into how to adapt your art space for performance and comfort, American Artist always couples artistic inspiration with instruction so that you can come away with a better sense of where to go on your own path as an artist.

Cotton or Linen

Canvas COTTON or LINEN?

Linen is by far the better-quality because of its strength and resistance to decay. Woven from flax, the weave can show throughout many layers of paint.

Primed with an oil primer this is the classical standard for oil paintings. An acrylic primer which is less expensive than oil primer, can be used with either acrylic or oil paints. Linen is difficult to prime and stretch properly, but it offers the smoothest and stiffest painting surface, one with proven longevity.

Linen, while expensive, is the traditional choice. Some of the qualities linen has that makes it so attractive to painters are:

• Linen is the most durable fabric to put paint on. Linen's warp and weft threads are equal in weight so less susceptible to the expanding/contracting problems created by moisture.

• Linen is very receptive to sizing and priming applications.

• Linen retains its natural oils which preserve the fiber's flexibility and keeps the canvas from becoming brittle.

• Linen has a more “natural” weaved finish than cotton and is available in a variety of textures, weights and smooth or rough finish.


Cotton is desirable because of its affordable price and its ease of stretching.

Cotton duck: Much less expensive than linen, it has become the most popular support for oil and acrylic painting, especially for students. A properly prepared cotton canvas has longevity similar to linen, and is more flexible and easier to stretch properly. However, cotton is considered too flexible for very large paintings.

It is possible to stretch cotton tighter than linen, without straining the wooden support, because cotton fibers stretch more easily than linen fibers. Although not as strong as linen, a heavy grade cotton can make up for its lack of strength with its weight.

For both oil and acrylic painting, an acrylic gesso primer is generally used

The Art Society of New Jersey

Welcome I have set up a trial Blog for our members. Let test it and be ready for the Fall Season.
Thank You Peter