Preamble
This is the fifty-eighth post in a new Art Resource series that specifically focuses on techniques used in creating artworks. For your convenience I have listed below all the posts in this new series:
Drawing Art
Painting Art - Part I
Painting Art - Part II
Painting Art - Part III
Painting Art - Part IV
Painting Art - Part V
Painting Art - Part VI
Home-Made Painting Art Materials
Quality in Ready-Made Artists' Supplies - Part I
Quality in Ready-Made Artists' Supplies - Part II
Quality in Ready-Made Artists' Supplies - Part III
Historical Notes on Art - Part I
Historical Notes on Art - Part II
Historical Notes on Art - Part III
Historical Notes on Art - Part IV
Historical Notes on Art - Part V
Tempera Painting
Oil Painting - Part I
Oil Painting - Part II
Oil Painting - Part III
Oil Painting - Part IV
Oil Painting - Part V
Oil Painting - Part VI
Pigments
Classification of Pigments - Part I
Classification of Pigments - Part II
Classification of Pigments - Part III
Pigments for Oil Painting
Pigments for Water Color
Pigments for Tempera Painting
Pigments for Pastel
Japanese Pigments
Pigments for Fresco Painting - Part I
Pigments for Fresco Painting - Part II
Selected Fresco Palette for Permanent Frescoes
Properties of Pigments in Common Use
Blue Pigments - Part I
Blue Pigments - Part II
Blue Pigments - Part III
Green Pigments - Part I
Green Pigments - Part II
Red Pigments - Part I
Red Pigments - Part II
Yellow Pigments - Part I
Yellow Pigments - Part II
Brown and Violet Pigments
Black Pigments
White Pigments - Part I
White Pigments - Part II
White Pigments - Part III
Inert Pigments
Permanence of Pigments: New Pigments - Part I
Permanence of Pigments: New Pigments - Part II
Limited or Restricted Palettes
Testing of Pigments - Part I
Testing of Pigments - Part II
Further Refinement of Pigments
There have been another one hundred and thirteen posts in a previous Art Resource series that have focused on the following topics:
(i) Units used in dyeing and printing of fabrics;
(ii) Occupational, health & safety issues in an art studio;
(iii) Color theories and color schemes;
(iv) Optical properties of fiber materials;
(v) General properties of fiber polymers and fibers - Part I to Part V;
(vi) Protein fibers;
(vii) Natural and man-made cellulosic fibers;
(viii) Fiber blends and melt spun fibers;
(ix) Fabric construction;
(x) Techniques and woven fibers;
(xi) Basic and figured weaves;
(xii) Pile, woven and knot pile fabrics;
(xiii) Durable press and wash-and-wear finishes;
(xvi) Classification of dyes and dye blends;
(xv) The general theory of printing.
To access any of the above resources, please click on the following link - Units Used in Dyeing and Printing of Fabrics. This link will highlight all of the one hundred and thirteen posts in the previous a are eight data bases on this blogspot, namely, the Glossary of Cultural and Architectural Terms, Timelines of Fabrics, Dyes and Other Stuff, A Fashion Data Base, the Glossary of Colors, Dyes, Inks, Pigments and Resins, the Glossary of Fabrics, Fibers, Finishes, Garments and Yarns, Glossary of Art, Artists, Art Motifs and Art Movements, Glossary of Paper, Photography, Printing, Prints and Publication Terms and the Glossary of Scientific Terms. All data bases in the future will be updated from time-to-time.
If you find any post on this blog site useful, you can save it or copy and paste it into your own "Word" document for your future reference. For example, Safari allows you to save a post (e.g., click on "File", click on "Print" and release, click on "PDF" and then click on "Save As" and release - and a PDF should appear where you have stored it). Safari also allows you to mail a post to a friend (click on "File", and then point cursor to "Mail Contents On This Page" and release). Either way, this or other posts on this site may be a useful Art Resource for you.
The new Art Resource series will be the first post in each calendar month. Remember - these Art Resource posts span information that will be useful for a home hobbyist to that required by a final year University Fine-Art student and so undoubtedly, some parts of any Art Resource post may appear far too technical for your needs (skip those mind boggling parts) and in other parts, it may be too simplistic with respect to your level of knowledge (ditto the skip). The trade-off between these two extremes will mean that Art Resource posts will be hopefully useful in parts to most, but unfortunately may not be satisfying to all!
Color and Light - Part I [1]
The color of a pigment is not one of its definite, inherent properties, rather it is the effect on the eye produced by that particular substance under certain circumstances. For example, color blindness is an often misunderstood condition. Many assume because of its name that “color blind” means a person can only see in black and white. In actuality, the vast majority of people with color blindness do see color, but they see a much narrower range of color. It is estimated that a person with normal color vision can see up to 1 million distinct shades of color, but a person who is color blind may see as few as just 10 thousand colors (i.e., 1% of the normal range).
Images that simulate color blindness, like the ones in this blog it can give an impression to people with normal color vision of what color blind people see, or answer the question - "What does the world look like to a color blind person?" However, these simulations actually fail to give a realistic understanding of a color blind person's experience.
So, what are the actual effects of color blindness on vision? The primary symptom that color blind people experience is color confusion. Put simply, color confusion is when someone mistakenly identifies a color, for example, calling something orange when it is actually green.
When a dry pigment is mixed with a liquid, its color is changed to a darker or deeper tone. This is an optical effect, which may be explained in the following manner. Materials used as pigments differ widely in certain properties from liquids used as mediums. One of these properties is the amount of light a substance reflects and absorbs. All liquids and solids vary from each other in this respect, and each one has been measured and tagged with a number called its refractive index. Scientifically, the refractive index is a measure of how much light bends (i.e., refracts), when it passes from one medium into another, and it is defined as the ratio of the speed of light in a vacuum to its speed in that medium. It is a dimensionless number, with a higher value indicating that light travels more slowly and is bent more sharply. The refractive index is determined by the material's optical density and depends on the wavelength and temperature of the light. For example, it must be taken into account when spearing a fish. The fish's apparent position in the water is not its actual position as explained in the diagram below.
The difference of the refractive index of air and water is such that the position of a fish in the water from a fisherman's point of view is the different from its actual position within the water, as per diagram below, because the difference between the refractive index of air and water which therefore bends the light.
A sheet of glass is a transparent substance; when a ray of light strikes it at an angle, there is a varying amount of surface, or mirror-like reflection, depending on conditions; however, the greater part of light passes through its continuous, uniform structure and emerges refracted or bent, at an angle different from which it entered. The refractive index is computed from this change of angle, which depends in each case on the substance's power to impede light rays.
Glass slab is a substance, or sheet made of a glass material having three dimensions: that is length, breadth, and height. It is cuboidal shaped. It does not deviate, nor does it disperse the light rays passing through it. This means that the incident and the emergent ray emerging from the glass slab are parallel. The glass slab only produces a lateral or (sideways) shift or displacement to the direction of light.
When two substances of varying refractive indices meet (see the above two examples), the greater the difference in their refractive indices, the greater will be the proportion of reflected light at the point where they meet. When a pigment with a refractive index of 2.00 is dry, each particle surrounded by air (the index of which is 1.00) causing a certain amount of white light to be reflected. When the pigment is moistened with linseed oil, which has a refractive index of 1.48, much less light is reflected, since more is absorbed, and so the pigment appears darker or more intense in hue.
As the light enters a film, we want to prevent it from reaching the substrate and exiting; the pigments do this by interacting with the light. When light interacts with a particle, there are five possible outcomes, namely: refraction, diffraction, absorption, reflection, or no change. All of these are considered scattering, except for the ‘no change’ situation. Refraction is when the light path is changed as it passes through the boundary of the particle and surrounding media. Diffraction is when the light is bent by interacting with the edge of the particle. Absorption is when the energy of the incident light is attenuated by the particle, but not necessarily by all frequencies equally. Reflection is when the light that hits the film returns to the source. We want to maximize scattering and minimize ‘no change’ to optimize hiding and color.
When transparent glass is pulverized, the powder appears white. Water in the form of ice is transparent; in the form of snow it is white and opaque. The reason for this is that while light rays are easily transmitted through uniform, continuous mediums of ice and the sheet of glass when they strike powdered glass and snow, they are reflected in all directions from the myriads of tiny facets of the particles surrounded by air, and are bent from one tiny particle to another until they become entirely diffused. When such broken planes and irregular facets exist ony on the surface, as when when a sheet of glass has been rubbed with an abrasive material to produce a ground-glass or non-transparent effect, the light is broken up and reflected on the surface, creating a whitish or frosted appearance. However, since the light-dispersing particles lie on the surface of a thin layer, the rays are not entirely impeded and continue on through the glass, which is now translucent instead of transparent.
Light reflected from shattered glass.
A flat or mat effect on a paint or varnish is always due to the fact that the surface consists of a thin layer of such irregular construction. When such a surface is moistened its opacity is temporarily diminished. In the same way, alumina hydrate, a white, opaque powder when dry will become colorless and transparent when wet with benzol, because particles are then surrounded by a medium which has a refractive index very close to its own. The effect of liquids upon the color and opacity of pigments varies greatly in each case, depending on the difference between the two refractive indices concerned.
Dry Alumina Hydrate.
If a pigment which appears transparent, or translucent, in a thinly applied layer is piled up or applied to a surface in a thick layer, it appears more opaque because the light then travels through a greater number of separate particles, each one of which impedes its progress by refracting it and also because there is more reflection of light from the points where the pigment particles and their surrounding medium meet, and because more particles absorb more light. Intensity of color also decreases the transparency or increases the hiding power of a pigment.
A thick application of paint appears more opaque because it can block more light, while a thinly applied layer is either translucent or transparent. While impasto is a technique that uses thick, textured paint for a dimensional effect, glazing is a technique that uses thin, transparent layers over an opaque base to create depth and luminosity.
The above section is a thin application of paint, whereas the section below is a thick application of the same paint. Note the difference in opaqueness.
Reference:
[1] The Artist's Handbook of Materials and Techniques, R. Mayer (ed. E. Smith) 4th Edition, Faber and Faber, London (1981).
This is the fifty-eighth post in a new Art Resource series that specifically focuses on techniques used in creating artworks. For your convenience I have listed below all the posts in this new series:
Drawing Art
Painting Art - Part I
Painting Art - Part II
Painting Art - Part III
Painting Art - Part IV
Painting Art - Part V
Painting Art - Part VI
Home-Made Painting Art Materials
Quality in Ready-Made Artists' Supplies - Part I
Quality in Ready-Made Artists' Supplies - Part II
Quality in Ready-Made Artists' Supplies - Part III
Historical Notes on Art - Part I
Historical Notes on Art - Part II
Historical Notes on Art - Part III
Historical Notes on Art - Part IV
Historical Notes on Art - Part V
Tempera Painting
Oil Painting - Part I
Oil Painting - Part II
Oil Painting - Part III
Oil Painting - Part IV
Oil Painting - Part V
Oil Painting - Part VI
Pigments
Classification of Pigments - Part I
Classification of Pigments - Part II
Classification of Pigments - Part III
Pigments for Oil Painting
Pigments for Water Color
Pigments for Tempera Painting
Pigments for Pastel
Japanese Pigments
Pigments for Fresco Painting - Part I
Pigments for Fresco Painting - Part II
Selected Fresco Palette for Permanent Frescoes
Properties of Pigments in Common Use
Blue Pigments - Part I
Blue Pigments - Part II
Blue Pigments - Part III
Green Pigments - Part I
Green Pigments - Part II
Red Pigments - Part I
Red Pigments - Part II
Yellow Pigments - Part I
Yellow Pigments - Part II
Brown and Violet Pigments
Black Pigments
White Pigments - Part I
White Pigments - Part II
White Pigments - Part III
Inert Pigments
Permanence of Pigments: New Pigments - Part I
Permanence of Pigments: New Pigments - Part II
Limited or Restricted Palettes
Testing of Pigments - Part I
Testing of Pigments - Part II
Further Refinement of Pigments
There have been another one hundred and thirteen posts in a previous Art Resource series that have focused on the following topics:
(i) Units used in dyeing and printing of fabrics;
(ii) Occupational, health & safety issues in an art studio;
(iii) Color theories and color schemes;
(iv) Optical properties of fiber materials;
(v) General properties of fiber polymers and fibers - Part I to Part V;
(vi) Protein fibers;
(vii) Natural and man-made cellulosic fibers;
(viii) Fiber blends and melt spun fibers;
(ix) Fabric construction;
(x) Techniques and woven fibers;
(xi) Basic and figured weaves;
(xii) Pile, woven and knot pile fabrics;
(xiii) Durable press and wash-and-wear finishes;
(xvi) Classification of dyes and dye blends;
(xv) The general theory of printing.
To access any of the above resources, please click on the following link - Units Used in Dyeing and Printing of Fabrics. This link will highlight all of the one hundred and thirteen posts in the previous a are eight data bases on this blogspot, namely, the Glossary of Cultural and Architectural Terms, Timelines of Fabrics, Dyes and Other Stuff, A Fashion Data Base, the Glossary of Colors, Dyes, Inks, Pigments and Resins, the Glossary of Fabrics, Fibers, Finishes, Garments and Yarns, Glossary of Art, Artists, Art Motifs and Art Movements, Glossary of Paper, Photography, Printing, Prints and Publication Terms and the Glossary of Scientific Terms. All data bases in the future will be updated from time-to-time.
If you find any post on this blog site useful, you can save it or copy and paste it into your own "Word" document for your future reference. For example, Safari allows you to save a post (e.g., click on "File", click on "Print" and release, click on "PDF" and then click on "Save As" and release - and a PDF should appear where you have stored it). Safari also allows you to mail a post to a friend (click on "File", and then point cursor to "Mail Contents On This Page" and release). Either way, this or other posts on this site may be a useful Art Resource for you.
The new Art Resource series will be the first post in each calendar month. Remember - these Art Resource posts span information that will be useful for a home hobbyist to that required by a final year University Fine-Art student and so undoubtedly, some parts of any Art Resource post may appear far too technical for your needs (skip those mind boggling parts) and in other parts, it may be too simplistic with respect to your level of knowledge (ditto the skip). The trade-off between these two extremes will mean that Art Resource posts will be hopefully useful in parts to most, but unfortunately may not be satisfying to all!
Color and Light - Part I [1]
The color of a pigment is not one of its definite, inherent properties, rather it is the effect on the eye produced by that particular substance under certain circumstances. For example, color blindness is an often misunderstood condition. Many assume because of its name that “color blind” means a person can only see in black and white. In actuality, the vast majority of people with color blindness do see color, but they see a much narrower range of color. It is estimated that a person with normal color vision can see up to 1 million distinct shades of color, but a person who is color blind may see as few as just 10 thousand colors (i.e., 1% of the normal range).
Images that simulate color blindness, like the ones in this blog it can give an impression to people with normal color vision of what color blind people see, or answer the question - "What does the world look like to a color blind person?" However, these simulations actually fail to give a realistic understanding of a color blind person's experience.
So, what are the actual effects of color blindness on vision? The primary symptom that color blind people experience is color confusion. Put simply, color confusion is when someone mistakenly identifies a color, for example, calling something orange when it is actually green.
When a dry pigment is mixed with a liquid, its color is changed to a darker or deeper tone. This is an optical effect, which may be explained in the following manner. Materials used as pigments differ widely in certain properties from liquids used as mediums. One of these properties is the amount of light a substance reflects and absorbs. All liquids and solids vary from each other in this respect, and each one has been measured and tagged with a number called its refractive index. Scientifically, the refractive index is a measure of how much light bends (i.e., refracts), when it passes from one medium into another, and it is defined as the ratio of the speed of light in a vacuum to its speed in that medium. It is a dimensionless number, with a higher value indicating that light travels more slowly and is bent more sharply. The refractive index is determined by the material's optical density and depends on the wavelength and temperature of the light. For example, it must be taken into account when spearing a fish. The fish's apparent position in the water is not its actual position as explained in the diagram below.
The difference of the refractive index of air and water is such that the position of a fish in the water from a fisherman's point of view is the different from its actual position within the water, as per diagram below, because the difference between the refractive index of air and water which therefore bends the light.
A sheet of glass is a transparent substance; when a ray of light strikes it at an angle, there is a varying amount of surface, or mirror-like reflection, depending on conditions; however, the greater part of light passes through its continuous, uniform structure and emerges refracted or bent, at an angle different from which it entered. The refractive index is computed from this change of angle, which depends in each case on the substance's power to impede light rays.
When two substances of varying refractive indices meet (see the above two examples), the greater the difference in their refractive indices, the greater will be the proportion of reflected light at the point where they meet. When a pigment with a refractive index of 2.00 is dry, each particle surrounded by air (the index of which is 1.00) causing a certain amount of white light to be reflected. When the pigment is moistened with linseed oil, which has a refractive index of 1.48, much less light is reflected, since more is absorbed, and so the pigment appears darker or more intense in hue.
When transparent glass is pulverized, the powder appears white. Water in the form of ice is transparent; in the form of snow it is white and opaque. The reason for this is that while light rays are easily transmitted through uniform, continuous mediums of ice and the sheet of glass when they strike powdered glass and snow, they are reflected in all directions from the myriads of tiny facets of the particles surrounded by air, and are bent from one tiny particle to another until they become entirely diffused. When such broken planes and irregular facets exist ony on the surface, as when when a sheet of glass has been rubbed with an abrasive material to produce a ground-glass or non-transparent effect, the light is broken up and reflected on the surface, creating a whitish or frosted appearance. However, since the light-dispersing particles lie on the surface of a thin layer, the rays are not entirely impeded and continue on through the glass, which is now translucent instead of transparent.
A flat or mat effect on a paint or varnish is always due to the fact that the surface consists of a thin layer of such irregular construction. When such a surface is moistened its opacity is temporarily diminished. In the same way, alumina hydrate, a white, opaque powder when dry will become colorless and transparent when wet with benzol, because particles are then surrounded by a medium which has a refractive index very close to its own. The effect of liquids upon the color and opacity of pigments varies greatly in each case, depending on the difference between the two refractive indices concerned.
If a pigment which appears transparent, or translucent, in a thinly applied layer is piled up or applied to a surface in a thick layer, it appears more opaque because the light then travels through a greater number of separate particles, each one of which impedes its progress by refracting it and also because there is more reflection of light from the points where the pigment particles and their surrounding medium meet, and because more particles absorb more light. Intensity of color also decreases the transparency or increases the hiding power of a pigment.
A thick application of paint appears more opaque because it can block more light, while a thinly applied layer is either translucent or transparent. While impasto is a technique that uses thick, textured paint for a dimensional effect, glazing is a technique that uses thin, transparent layers over an opaque base to create depth and luminosity.
Reference:
[1] The Artist's Handbook of Materials and Techniques, R. Mayer (ed. E. Smith) 4th Edition, Faber and Faber, London (1981).
