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Q. What does ASTM mean?

A. American Society of Testing and Materials, subcommittee DO1.57 rates pigments according to lightfastness criteria; color will remain constant for 125 years when maintained at art gallery conditions.

Q. What do you need to know about color lightfastness and permanence?

A. Colors are rated according to lightfastness (ASTM I, II, II, etc.). Professional artists and teachers generally use, and recommend that students use, ASTM I and II rated colors. Light (ultra-violet waves) is the chief factor that can cause deterioration of degradation of color. However, it is important to remember that other factors such as humidity, paper content, and alkaline or acidic conditions can also affect color and paper.

Colors with a rating of III or higher are considered to be “fugitive”. This means that they have the tendency to fade considerably over relatively short periods of time (less than 20 years). Manufacturers of artist color continue to make fugitive colors usually because it is a traditional color for which no synthetic replacement has been found.

Q. What makes a paint permanent?

A. Pigment that is lightfast, alkaline and acid resistant.

Q. What makes a color lightfast?

A. The pigment. Most traditional organic (vegetable or animal products) have been replaced by modern chemically produced ones;. these are called the Synthetic Organics. Pigment manufacturers are looking for constancy and reliability in a pigment. Paint manufacturers wanting the same thing, buy their pigments from them to produce paints, whether it be wc, acrylic, or oil paint.


Q. What is Watercolor painting?

A. The technique is based on the application of transparent layers of water-soluble paint onto brilliant white paper. The technique utilizes the whiteness of the paper for its whites and lightness, as diluted colored paint layers, or glazes are applied in transparent layers over the white surface they create rich, luminous color.

Q. What are watercolors made of?

A. It is paint made of water-soluble Binding Agent and Pigment

Q.What is the binder for watercolor?

A. Gum Arabic. Gum Arabic is a resinous binding agent derived from the several varieties of Acacia Tree. Incisions are made in the bark of the tree and the resinous sap is exuded. Sennelier selects the highest quality gum from trees in Sudan, Africa specifically from Kordofan. Retained in its raw natural state, in large chunks rather than powdered the gum is dissolved slowly in cold water, preserving its maximum binding strength. Once dissolved, a resin rich solution (50-60%) results.

In addition to gum arabic tube watercolors also include:

Glycerin: The gum arabic alone when dry is brittle so glycerin is added which gives plasticity to the mixture. Glycerin is a clear colorless non toxic, non volatile, syrupy alcohol (trihydroxide alcohol) which is used specifically in watercolor paints to placticize the brittle binders used in their manufacture. It prevents extreme drying or flaking of paint, improves brushability and solubility of paints.

Honey: Added to the gum arabic and water solution to impart distinctive luster to the certain colors. Also acts as plasticizer and contributes to overall smoothness of the paints both in grinding and painting. Can be used to formulate the paints so that they stay semi-moist in cake form.

Q. As a watercolorist, what do you need to know about paper?

A. Its content. Its surface type. Its weight. Each of these considerations affects the absorbency and way that the paint appears on the surface of the paper.

Q. What are the different types of Watercolor Paper

A.The surface texture is determined by the way it is treated after the pulp is taken from the mold.

Hot Pressed
Fine grained, the smoothest surface, is pressed between two heated rollers. This paper is considered difficult to work on because of its slick surface, and its tendency to dry quickly. The paper, when properly controlled does have great luminosity.

Soft Pressed
An exclusive surface recently created by Fabriano in cooperation with Savoir-Faire as a response to the techniques and aesthetic needs of artists today. Texture between HP and CP surfaces. Light surface sizing, internally sized creates absorbent but very workable surface. Great luminosity of color.

Cold Pressed
Medium grained, has more surface texture than HP, sometimes called “Not” (meaning not Hot Pressed.) The surface is slightly textured, allows for slower drying time because paint is not absorbed as quickly as with smoother HP. Paint flows over surface easily, but does not slide or soak in as on HP.

The most coarse, textured surface of the three types, the least pressure is applied to this paper as it comes out of mold and is rolled between felts. Sparkles of white show because paint does not cover as easily or evenly as on HP or CP.

Q. What does “weight” mean when it comes to paper?

A. 140lb, 300lb most suitable for watercolor. Under 140 lb is generally too light weight and will buckle when wet. 140lb. is a good weight for most painters. When stretched the buckling is easily controlled, and many painters find it heavy enough to paint on without taping. 140lbs refers to the weight of a ream (500 sheets) of 22”x30” paper. The European measurement refers to the ratio between grams and one square meter.

200gsm = 90lb
300gsm = 140lb
640gsm = 300lbs


Q. What is egg tempera?

A. Before oil painting, egg tempera was the predominant painting medium in the 14th century. Egg tempera is water soluble and permanent. It is a highly pigmented, fine art color alternative to oil paints. It is bound with a centuries old egg emulsion recipe, giving a satin-matt finish that is water resistant when dry.

Q. What should I paint on when using Egg Tempera?

A. Sennelier egg tempera colors hold their brush strokes, and do not change when dry. A relatively flexible paint film when dry, however egg tempera is more brittle than oil paint. Because of this, sized and acrylic primed Wood Panels are the support of choice. However non-greasy supports like acrylic primed canvas or acrylic gessoed paper can also be used. If using unprimed canvas, archival paper or museum board, they should be mounted onto the wood panel. If the work is carefully handled, 300 lb. Fabriano paper can be used unmounted, as long as the finished work is never bowed or bent. Wood panels should be sealed with Lascaux Fixative or Lascaux Sealer, followed by Lascaux Acrylic Gesso. Oil based primers are not recommended.


Q. What are oil pastels made of?

A. A microcrystalline wax that is composed entirely of carbon and hydrogen, derived from a petroleum base. Its fine crystalline composition gives the pastels the ability to hold the oil in the pastels exceptionally well, as well as giving them good flexibility and suppleness.

Q. How are oil pastels used?

A. Sennelier oil pastels can be applied to any paper, rigid support or fabric support without technical restraints, allowing the artist complete freedom of expression while maintaining archival stability. When drawing is complete surface may be protected with Sennelier oil pastel fixative.

Q. How long does it take for oil pastels to dry?

A. They never dry and thus will never crack. The reason for this is that the oil pastels contain no oxidants. This guarantees the preservation of the color intensity of the pigments without yellowing or cracking, and prevents the deterioration of the surface or support.

Q. Are oil pastels acid free?

A. Yes. Oil Pastels are completely acid free


Q. What is the difference between a soft pastel and a hard pastel?

A. Pastels are made by blending dry powdered pigments with a non-greasy binding agent. They dissolve with water and are available in different degrees of hardness. Soft pastels usually contain more pigment, are softer and have more intense colors. Only Sennelier soft pastels do not contain clay, which mutes the color. Hard pastels contain less pigment, are harder and always contain clay, which makes them hard and have less intense color. Hard pastels do not crumble as easily as soft pastels and are easier to work with.

Q. Are Sennelier pastels lightfast?

A. Yes. Of 525 Sennelier Soft Pastels only 20 are rated Lightfast Rating III (fugitive color, see above).

Q. Why do Sennelier pastels vary in hardness, softness and brittleness?

A. Sennelier Soft Pastels are a combination of pigment and binder, for dark and medium tones; and a combination of pigment, binder and chalk for light tones. They contain no additives, fillers or clays. They vary in consistency because each pigment varies in consistency. Some pigments are harder than others, some softer and some more brittle. Each color is allowed to achieve its maximum color intensity without additives. The true nature of the pigment is allowed to influence the color.

Q. Is there a difference between full-stick and half-stick pastels other than the size?

A. No. The only difference is thickness, length and label. Half sticks are a little thicker but shorter so artists can purchase a larger variety of colors at a reduced price. There is no label since the stick is shorter.


Q. How do I determine the quality of a brush?

A. Compare the same type of hair, shape and size from different manufacturers.

1. Feel the hair. Which hair is thicker, softer, rougher? Not all Kolinsky Sable or Sable hairs are the same. Inferior Kolinsky Sable will not be as soft and thick as high quality Kolinsky Sable.
2. Spread the hair. Using your thumb and index finger spread the hairs out. Which brush hair spreads out most evenly and symmetrical. Which has thicker tuft and more hairs to spread out? Less expensive brushes often will have less hair and gaps will show during this testing.
3. Flip the hair. Is the progression from front to back even and symmetrical?
4. Scrub the hair. Scrub brush into palm of your hand. What type of spring does the brush have? How does the tuft of hair spread out evenly? Inferior Bristle will have poor resistance and will fan out on your palm unevenly.

Q. What are the different types of brush hairs/fibers?

A. There are three categories, which differ in shape, diameter and flag.

HAIRS: Hydrophilic. Conical and single flag. Have a “belly” that begins at the center of the hair length and then becomes gradually tighter. There are two categories of hair: Extra-Fine (kolinsky sable, sable and squirrel) and Fine (ox hair, polecat, pony, goat, etc.).
HOG BRISTLES: Interlocked (curved) or Boiled (straight). Multiple flag. White or half-white.
SYNTHETIC FIBER: Hydrophobic. Straight, curved and tapered. Up to 7 diameters used.

Q. What is the difference between natural and synthetic hair?

A. Natural hair brushes are able to hold more paint, retain their shape longer, have more spring, and distribute the paint more evenly than synthetic hair brushes.

Natural hair brushes are hydroscopic with millions of microscopic “scales” on the surface of each hair. Natural hair not only is able to absorb water but the “scales” enable paint to adhere to each hair and distribute the paint evenly and consistently during the brushstroke. In addition natural hair brushes, such as sable, have a thick belly and tapered point enabling the brush to retain its shape for a longer period of time.

Q. How does brush hair affect brush stroke?

A. Since natural hair brushes are hydroscopic (absorb water) and have “scales”, they not only absorb water but also are able to have paint adhere evenly to each brush hair. During the brush stroke the paint is then evenly distributed. Synthetic brushes are hydrophobic (do not absorb water) and have no “scales”. The paint slides along each filament during the brush stroke resulting in an uneven brush mark.

Q. What is Kolinsky Sable and how does it differ from regular Sable?

A. Kolinsky Sable is the highest quality “sable”. The hair is the longest, densest and most luxurious, enabling the hair to hold more water, have better spring and be most sensitive to the artists touch. Sable or Red Sable is similar to Kolinsky Sable but while being soft, fine and with good spring, it cannot match the superior quality of the Kolinsky Sable.