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Oil Paint
Uncompromising quality

Oil paintings are most likely one the most favored medium of collectors due to their affluent appearance and durability. Rewards from painting in oil are very satisfying as long as you stick by the rules. It is important to understand the properties of the materials used in this medium before using it otherwise the painstaking efforts of your work may ferment into disaster. Even when your completed work has met your standards, over a period of time your masterpiece could self-destruct due to the procedure you had used while creating it.

The Farm  1666
Oil on canvas
Adriaen van de Velde

One of the most common errors made is the use of Rabbit Skin glue sizing and not allowing for adequate drying time when using an  Acrylic Gesso ground. Rabbit skin glue will allow the damaging absorption of moisture and  it is also believed that rabbit skin glue  has different expansion and contraction properties than oils which will cause cracking. Acrylic Gesso is a premium water based/soluble paint. However, if moisture remaining in this ground is not allowed to evaporate off and is painted over with an oil based paint, it becomes sealed between the layers of the paint and the size. Since this moisture will seek a means to escape (especially on warm days) it will  eventually cause blisters and cracking. I personal use Rabbit Skin Glue and Acrylic Gesso only for water based paints. The suggested alternative is to use a neutral pH  PVA (poly vinyl acetate glue) such as Gamblin PVA Sizing and two to three coats of an oil base primer (alkin resin binder) such as Gamblin Oil Painting Ground

Another mistake all to often made with oil paintings is the inconsistency of mixing paint medium.  Oil paint, inherently known for it’s slow drying time, is made by mixing the color pigment in a binder of  flax linseed or sunflower oil that absorbs oxygen as it polymerizes and moves expanding and contracting as it dries into a tough film known as linoxyn. A similar consequence of blisters and cracking is caused when an excessively fat layer of paint is painted over with a layer containing less oil than the previous one (known as lean-over-fat) or when driers have been added to the top layer where the linseed oil binder is sealed between dry and hardened layers of paint or the top finish. Due to the  movements of the under layer while drying, the top film that has completely dried and hardened becomes forced  to move with the under layers causing it to crack. Understanding these properties and using each layer to your advantage (especially with transparencies) is one of the secrets to successful painting with oils.

Pigments

Properties artist’s admire about painting with oils is it’s buttery smooth texture as it’s carried on a brush. The old masters ground and blended their pigment in dry state before mixing with their medium. You can still obtain dry pigments to use in your paint but it is much more convenient and safer to use them from a tube. The pigment colors are rich and maintain their purity indefinitely and since the colors from the tube have been ground in linseed oil they can be applied to the canvas straight from the tube, mixed with a compatible medium or thinned with the appropriate solvent. I personally hold back on the linseed oil in my medium (see below) because of how it retards drying and because there is already adequate quantities ground into tube pigments. If there is a need to alter my medium such to ad resins I place the pigment on a paper towel first to draw out the excess linseed oil first

Mediums

Traditional mediums are a mixture of ingredients that consist of or are compatible with the binder. Although linseed oil thinned moderately with turpentine serves well as a medium by itself the mixture generally consists of variable ratios using Stand oil or sun-thickened linseed oil, Damar resin varnish and turpentine. Many other versions of these elements for mediums have been created to improve certain characteristics of the paint for specific requirements (see below). Stand oil is responsible for maintaining the paint’s flexibility where resins such as Damar contribute to it’s toughness or sheen. Turpentine is primarily used as the solvent to thin or dissolve the solid components to blend the pigment into a uniform mixture.

The simple example recipe for mixing your own medium is as follows:

1 to 3 parts stand oil or sun-thickened linseed oil
1 part Damar Varnish
3 to 7 parts turpentine

Damar can be dissolved by turpentine after the paint has dried, so it’s ratio with the linseed oil should be no greater than 1 to 1. Use of an increased ratio of sun-thickened linseed oil will speed drying were as the same action with stand oil will slow drying. In order to maintain a standardized mix of your medium for your entire painting, it is advised to make up your medium (approximately 8-16 oz..) prior to starting your painting and store it in a clean sealable glass jar. While  following a process  known as painting the “Fat-Over-Lean” rule, thin again moderately with  turpentine to desired consistency, decreasing the amount of turpentine with each fresh layer. Note: Many artists have revised their medium formulas to avoid the excess use of turpentine for paint thinning or replaced the use of Damar with Copal or other resins starting from the  imprimatura because it starts building a tough paint film that dries quickly. The one detail always to consider when adding any material to your oil medium especially on a canvas support is, how it will alter the already tough and flexible film that linseed oil provides. 

A few drops of cobalt or Japan drier can be added as you are mixing your colors for faster drying but it should only be added to the first few layers and never to the final layers of paint. This will cause unequal drying or “crusting” as discussed previously where the top layer of film will dry preventing air to reach the paint below it eventually responsible for surface cracking. Each layer of paint film should be ground with an identical consistency throughout  or contain an increasing amount of oil in it’s medium so that each paint layer becomes more flexible than the layer beneath allowing uniform curing of the paint film. Look forward to allowing months for this method to dry before applying any form of finish.

Miscellaneous additives designed to improve paint medium properties:

Varnish Resins

Most traditional oil painting processes utilize natural resin varnishes which are added to mediums to intensify the color of oil pigments, as protective transparent layers between coats of paint, to retouch the surface “flat spots” of paint, or as a sealant for the final  finished painting. This is usually done by dissolving the gum in turpentine and blending with linseed or stand oil.

Damar a soft resin is produced from the sap of an Asian fir tree and provides a deep gloss, with  impressive adhesion, flexibility and resistance properties. Dissolved in equal parts of turpentine Damar Gum Varnish is probably the easiest of all  clear varnishes to make and is most commonly used in retouch varnish and as a hardener with encaustic painting mediums. Because damar is not completely soluble in mineral spirits, only pure gum  turpentine should be used. It must also be noted as well that in the conclusion of in depth analytical research of several renaissance masterpieces that damar has an inferior resistance to solvents used during cleaning/ restoration practices and is prone to cracking and disintegration with age. In conclusion it is best suited as a removable finish.

Amber resin mediums were also used by oil painters throughout Europe during the  renaissance periods. It is believed to be the Flemish artist’s favorite which was blended once dissolved with sun thickened (co-polymerized) linseed or stand oil.

Copal resin mediums strengthen the binder of oil paint  It is the only resin used that has proven itself through time providing increased resistance against the elements by hardening the paint film as it cures. When used throughout the layers of  the painting this varnish resin becomes part of the paint eliminating the need for a protective coat of varnish. A little goes a long way with amber and copal resin. If using on a flexible support,  excessive use may create a brittle, cracking film. Although fortunately it can be purchased premixed, blending this scarce resin is sometimes a dangerous process for the artist due to the need for use of heat with a flammable solvent. The only draw back with using many of the the premixed versions is that synthetic resins are blended with actually only a small percentage of Copal in these mediums. Always read the labels before purchase.

Balsam Resin diluted in mediums with Venice Turpentine is used to  provide a lustrous glow. However it not always easy to find. Also a soft resin it has the same performance and durability characteristics as Damar.

Retouch Varnish  is used create a fresh surface to adhere to when using oil paints  over an older dry and absorbent layer. This varnish also restores luster  to “oiled out” or dulled areas of color caused by heavy dilution, lack of medium or an insufficient “absorbent” ground.

Oils

Venice Turpentine from the Larch Pine is only indigenous to the hilly regions and large forests of the Alps  throughout Central Europe. Produced now mainly in the Tyrol, Switzerland, and Piedmont but since it was formerly exclusively exported from Venice it has become known as Venetian Turpentine.  It has been used in medicine and for making several types of varnishes. The sap of this of material is collected from full-grown trees and is perfectly clear and needs no further preparation than straining  to remove  impurities. Adding to oil paint mediums and varnishes creates a deep, tough enamel like surface.   It should be diluted only with Turpentine and used sparingly.

Stand Oil is nothing more than “cooked” refined  linseed oil designed to prevent yellowing and thicken the medium and does not work well on it’s own, but blends well with damar, copal, and amber resins dissolved in turpentine.

Cold Pressed Sun Thickened Linseed Oil actually produced from the flax seed is used  for thinning, improving gloss, transparency, and smoothing brush marks.

It is believed that this was ultimately the main ingredient of the old masters when it was sun thickened and beached while exposed to air to get a head start on the polymerization before using it on canvas. Louis R. Velasquez inspired by his mentor Frederic Taubes provides insight in his book from a considerable amount of valuable research on this topic. He also covers the advantages of using calcium carbonate and egg white glair blended with linseed oil as a medium. Oil Painting with Calcite Sun OilOil Painting with
‘Calcite Sun Oil’:
Louis R. Valasquez

Lavender Oil is a retarder and thinner. Used  with varnishes to smooth out brush marks by allowing the paint to flow, it’s properties are similar to turpentine. Spike oil is different variety of Lavender oil also used as a dryer.

Poppy Oil is slow drying , and more transparent. It is less likely to yellow than linseed oil, and is used with white or pale colors. However, this very light oil dries slowly and is prone to cracking.

Refined Safflower Oil dries similar to poppy seed oil but is very clear and non yellowing. Most suitable for whites and light colors to improve flow, Safflower oil is also prone to cracking.

Walnut Oil properties are  similar to linseed oil. Non yellowing and having a good drying rate history, was believed to be a superior replacement binder to linseed oil but there are studies available that prove otherwise. It will eventually darken with age.

Thinners

Thinners used in oil painting are organic distillates and linseed oil. Used primarily as a binder unrefined linseed oil works best. The draw back is the drying time required if too much is used. Faster drying solvents also thin oil paint by dilution.

Traditionally, Distilled Turpentine is the  best solvent to use for fine art when painting with oils. The main reason for this is that linseed oil, damar and all varnish resins are all extracted from plant sap resins which  contain similar compatible properties as turpentine when used in the paint medium. However, use should be utilized sparingly as use of too much turpentine breaks down the composition and undermines the durability of the paint film.

Petroleum based distilled paint thinner such as mineral spirits should be left to be used for petroleum tasks such as cleaning auto carburetors and brake parts not with painting. Since they are refined from petroleum fossil oils they will only evaporate without  absorbing any oxygen vitally necessary to the paint polymerization process. To further clarify, fossil extractions combine oils of plants, ancient animal fats as well as several geological minerals and unknown contaminates that plant sap resins have just not had enough time to absorb. Yes, mineral spirits can be used but it is not necessarily as pure or compatible with paint binder oils or resins as Distilled Turpentine or Spike oil.

Safety: Consistently remind yourself in the course of your painting sessions that the majority of the organic distillates used in oil paints are designated as Flammable. Handle them cautiously keeping them clear of any possible ignition source. For those who dislike the odor or are concerned about the health hazards from paint solvents, you should be certain you are painting with adequate ventilation. Additionally, an odorless solvent is not a “safer”  alternative. The evaporation properties and toxicity levels are exactly the same. There are also inexpensive air filters (Nox Out) which will remove your work area of harmful fumes.

Driers

Most paint manufacturers add drying catalysts to standardize the dry time of  their products. For artist paints drier metals such as  Lead, Cobalt, Manganese, Barium, and Calcium are used. One of the oldest metals used, lead is said to dry the paint uniformly from within preventing skinning that will blister and crack. Calcium Carbonate is a safe alternative which also accelerates polymerization of the paint film.

The most commonly used Cobalt and Japan driers should be restricted for use with lean glazes or washes when building depth and with transparency techniques. When used in minute amounts they accelerate polymerization  and are intended to speed up drying of each thin layer before applying the next. Overuse with oil paints especially with fat mediums has been associated as a cause for surface wrinkling.

When thick painting methods or palette knife techniques are used in Impasto techniques or Alla Prima,  sometimes a translucent gel such as Liquin Impasto, or Gamblin Galkyd Gel Medium are used. The addition of driers to these mediums is not recommended. Grumbacher Zec is a  colorless gel drier that preserves consistency while accelerating drying time.

Alkyd Resins

Modern mediums have been under development since the turn of the century  to   improve the use of oil based medium without sacrificing it’s traditional beauty and durability. Major accomplishments have been obtained by providing the convenience of decreased drying times and the development of water soluble paints which lower environmental toxicity concerns as well as possible long term health effects from exposure of aromatic solvents. Keep in mind however, that not unlike the development of Acrylics, these mediums have not yet been exposed to the test of time.

Grumbacher Alkyd Painting Medium, Utrecht Alkyd Glaze and Gamblin Galkyd are a few synthetic resin mediums designed to allow an artist to complete a painting much faster than using traditional mediums.  These new ready to use products are usually dry to touch within 6 to 8 hours and thoroughly dry within 20 hours which allows another layer to be painted over the next day. They can be used from the bottle, thinned with linseed oil, mineral spirits or turpentine. However, adding large amounts of linseed oil will retard drying.

Water Soluble Oils

Grumbacher’s Max oil colors are made from the same pigments and linseed oil as any oil based paint except they possess one additional characteristic. They are also water soluble. They perform the same and can be mixed with any other oil colors, mediums, thinners, gels, or driers. As long as your additional mixed proportion contains no more than 30% of traditional oil colors or mediums overall, Max  will retain it’s water soluble properties. This means that your medium can be thinned with water  if you  prefer and when you have finished your painting session your brushes can be cleaned up with soap and water.

Experimenting to find how to use these materials where they suit your own painting style is your best bet. That’s part of the fun of being an artist but you should always remain mindful about the archive qualities of your mediums to assure the quality of your work. To get a better understanding of how you can blend your mediums and how they respond try the informative  MEDIA TABLE OF MIXED OIL, RESIN AND BALSAM .

Oil Painting Safety & Health

Some oil base paints contain harmful additives, pigments and solvents. Although I should address safety first, it is also important for you to understand that with proper care and hygiene most of these hazardous paints can be used with out causing you any harm. Refer to this PDF about USING ARTISTS’ PAINTS for known hazards of pigments, resin sand solvents. Have you seen these labels on any materials you have purchased ?

Read the  ASTM International abstract to find out what they mean.

Links About Painting with Oils

Painting Lessons On Cd And Dvd. Andre Grobler Share 43 Years Of Professional Painting.

Winsor & Newton “The Oil Colour Book” 

Donald A. Jusko, Teaching Painting on Location

National Oil and Acrylic Painters’ Society

Oil Painters of America

Art training site on the web. A. Antonov’s Internet Classical Realism Art School.

Traditional Amber Resin, Natural Resin Base Varnishes and Painting Medium

“OIL PAINTING with “CALCITE SUN OIL” by Louis R. Velasquez

Historical Oil Painting Varnishes and Mediums

“Painting is the grandchild of nature. It is related to God.
Rembrandt van Rijn

 

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