Stabilizers and other ingredients Adulterants?
It is easy for artist's to believe that paint should be only pigment and a binder. It is true that dishonest manufacturers can boost profits by exchanging cheap materials for the expensive pigments that artist's expect. It happens commonly, but perhaps not nearly as often as some artist's believe. The inclusion of other ingredients has been a necessary part of making paint for centuries for good reason. Gouache without chalk added is not gouache, and in oil paint some pigments become stringy without the addition of stabilizers. Ultramarine Blue is one of the worst in this regard. In Renaissance times beeswax assumed this role as a stabilizer and was not considered an adulterant. Nowadays it is likely to be Aluminum Stearate that is added because artist's expect all oil paints to be uniformly short and buttery and metallic soaps like this do a very good job of that.

Unfortunately they have a down side, first of all they diminish the color intensity of the pigment and secondly they have been associated with embrittlement of old paint and also with yellowing of the paint film. Where their use is at a bare minimum these risks are very small, but in larger quantities they can be very harmful indeed, and there is a lot of financial incentive to add more than less. Because I understand that most artist's seem to prefer their colors to be uniformly buttery I cannot condemn these practices outright for pigments that are problematic, although it is harder to justify for all oil colors.

While stabilizes can be justified in some cases there are many inert pigment like ingredients that are present only for bulk, they are usually referred to as extenders or fillers. An addition of just 5% Barytes to a pigment may be almost unnoticeable to the average artist, yet over thousands of tubes produce significant savings for the maker.

Driers over used can be damaging to paint as well, but some colors can be very poor driers in oil without a little artificial help. The old masters got around this by adding the fast drying pigments such as those lead based or containing Manganese such as Umber to mixtures of slower drying colors. Siccatives such as Lead cooked into oil were known and used from early times, but even then were regarded as undesirable in paint generally although they seem to have used Vitriol as a drier for glazing. Or they simply accepted that some colors were going to take a long time to dry. Time was often not an issue anyway back then. Now that few artist's use White Lead or genuine Naples Yellow, and we live in a fast paced world there is a strong need for driers in many instances. Problem is that indiscriminate use is common in an effort to achieve paint consistency.

The maker of paint in the studio has then the choice to do as the old masters did and use a minimum of any additives and accept the differences between colors. Some pigments such as Ultramarine will become less easy to handle on the brush, but the increase in color intensity will be obvious and enjoyed. There will be other colors with less noticeable difference, but all colors will show some difference. Most painters who make their own paint prefer the simpler approach, or perhaps choose a paint medium that requires no additives in the first place like Tempera. The choice is yours.

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Inert pigments The uses of extenders & fillers
There are many inert pigments that find their way into paint tubes as both extenders and fillers and there is a fine line between the two. A filler is just what it's name implies, a substance intended as a solid component in a paint tube in place of a more expensive color pigment. An extender on the other hand is more complex and often plays an important role in the formulation of artist's paint. Pthalocyanine for example is such a powerful coloring agent that its use on the palette would be almost impossible without the legitimate addition of up to 70% alumina hydrate during manufacture. Gouache as previously mentioned would cease to be gouache without the addition of chalk as an extender that renders all colors opaque. Pencils, pastels and chalks are all artist's materials that depend on various inert pigments to create the degree of hardness necessary to make the drawing material.

The artist making paints and other art materials in the studio will come across many circumstances where these substances are a necessary part of making the art material of their choice, however they are also in the unique position of being able to limit their use to the necessary minimum and consequently enjoy greater clarity of tone and stronger, more pure colors than are commonly available for purchase in stores. The inert pigments commonly used in industry and likely to be used by an artist making their own materials from time to time are:

  • Precipitated Chalk
  • Whiting
  • Kaolin
  • Talc
  • Silica
  • Pumice
  • Marble Dust

Whiting, Marble Dust and Precipitated Chalk are identical chemically but have a markedly different crystalline structure. Precipitated Chalk is superior in all ways for most purposes in making the best possible paints. Silica and Pumice are mostly used just to impart a tooth to materials.

Glass beads and other 'textural' fillers.
Glass beads have become a common textural substance that are too large to be called pigments so technically are simply fillers. Acrylic paint is particularly suited to using these sorts of additives. Sawdust, sand, marble chip, vermiculite, even kitty litter are just a few of the many small substances that can be added to acrylics for effect.

Go to the Inert Pigments page for more detailed information

Stabilizers Necessary for oil paint
A stabilizer stops the pigment separating from the oil over time. When colors are stored for long periods in tubes this can be a significant issue. Stabilizers also help a paint to have a stiff buttery viscosity, a property described as being 'short' Some pigments are naturally the opposite when made into a paint. Ultramarine is the worst offender with this, making very stringy paint without the use of a stabilizer, and so the Renaissance masters added wax and the formulation described on this site includes beeswax as an acceptable additive. The beeswax should be the refined white type. This wax has had all impurities removed and then has been bleached in the sun and is therefore suitable for use in paints without discoloring the finished product.

Aluminum Stearate
Industrial stabilizers like Aluminum Stearate or Zinc Stearate should be avoided in studio made paint. They are specialized materials and not absolutely necessary as the older practice of using beeswax works just as well. If you do use them they certainly do a good job of thickening the paint to a buttery consistency and prevent the separation of pigment and binder in the tube. The recommendation against then is not that they don't do the job, it is more about maximizing purity of pigment color and strength which means minimizing any additive. Because beeswax is heavier than Aluminum Stearate 2% Beeswax is a lot less additive in the tube than 2% Aluminum Stearate.

Driers Also called siccatives
Siccatif de Haarlem and Siccatif de Courtrai are old time driers that should be avoided, along with another old master favorite Verdigris.

Vitriol is a Renaissance oddity in that its main ingredient (Zinc Sulfate) is not a drier at all, and it is believed that the drying action came from impurities such as Manganese. Modern Zinc Sulfate is too pure to be used as a drier.

Black Oil
Some recipes for so-called old master paints call for the preparation of litharge cooked into oil and sometimes called Black Oil. This practice is very hazardous and is regarded by many to lead to excessive darkening of the paint film over time. it needs to be treated with caution.

Cobalt Linoleate and Cobalt Napthalenate
The drier that is considered to be the least harmful to paint is Cobalt Napthenate or Cobalt Linoleate. It should be added if desired very sparingly to Linseed Oil paints only as paints made with Poppy Oil are more likely to crack with driers added. It is probably safest to keep to the Renaissance practice of only using driers as a direct additive to glazing mixtures and not actually adding them to the paint itself as making it. For many artists it is only the Cadmium's that might be problematic in regard to drying times in oil. Those artist's who use Alkyd mediums while painting shouldn't need any additional siccatives at all.

Size A type of glue
A size is a solution that is applied to a surface that either seals the surface or is mixed with chalk to provide a ground. A good size should permeate the surface not just adhere to the outside. For paintings the size is either hide glue or gelatin. Gelatin is most commonly used for sizing paper even today, but sizes and hide glue gesso's have been replaced by Acrylic gesso for canvas and wood panels in most cases. Egg Tempera however requires the particular absorbency of hide glue chalk gesso for best results.

Hide Glue - also called Rabbitskin Glue
All the early writers emphasize the necessity of using fresh hide as the glue made from older stock is not so strong as that made from fresher. These days with the reduction in the use of hide glue by artist's stocks are often old. Examine any well to judge freshness. I have observed stocks from famous European manufacturers that is clearly much older than stocks from a smaller but local company. There is no hard and fast rule here, price and old world reputations mean little beside the evidence of your eyes and nose.

Cennini advised a method of using parchment scraps, but in an age of little parchment being made we use either rabbitskin or calfskin. it comes in sheets or rough pieces, or granulated or powdered. Powdered is probably easiest to use but can easily have a portion of bone and hoof glue added without a way of telling. At least the rough sheets are clearly what they pretend to be. I also find it is easier to judge the freshness of the hide in the sheet form. Before use it must be broken into small pieces.

Gelatin is closely related to Hide glue but it is sourced from the bones and hooves of the animal as well as the skin and so has a slightly different composition. It is not as strong as hide glue. The food grade gelatin purchased from supermarkets should never be used. Instead high grade leaf gelatin should be the only choice.

Go directly to the demonstration of how to make paint

Go to the Pigments page

Go to the Binders page

Go to the Solvents page

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