This is the fifth Investigation of the LabLearner CELL Science and Art. In it, students continue the exploration of perspective and the illusion of depth in paintings. In addition, students will study the use of color in painting to achieve a sense of depth and emotion. 

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Artists paint things they see in the world around them. This slide emphasizes that common objects (fruit in this example) come in a range of colors representing the entire visual spectrum, from the grapes and plum in the blue/violet region of the spectrum on the left to the apple and strawberry at the far right of the spectrum. Oranges, yellows, and greens are also represented at the appropriate place along the visual spectrum. 

It is the artist’s job to use paints to mimic the colors that appear in nature closely. Artists are able to mix all of the multitude of colors that they see with a manageable number of basic colors. Creating new colors by mixing a few basic colors together is one of the awesome skills that artists are trained to do.

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Artists mix their paints on a thin piece of wood or plastic called a palette (a typical wooden palette is shown on this slide). The slide shows how a few “primary” colors can be mixed to produce additional colors (secondary colors). For paints, the primary colors are yellow, red, and blue. These primary colors, in turn, can be mixed together, as shown on the slide. Thus, mixing the two primary colors, blue and yellow, produces green. Mixing red and yellow results in orange. Finally, mixing red and blue gives us violet/purple.

Each of these secondary colors can again be mixed with other secondary or primary colors to make additional color combinations, reproducing the full visual spectrum of colors to represent the world as seen by the artist.

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This slide presents a color wheel, which provides a quick reference for mixing paint colors. Notice that the three primary colors are yellow, red, and blue and are marked with “P“s on the wheel. As can be seen, any of these three primary colors can be mixed to produce one of the three secondary colors (orange, green, and purple/violet), marked with an “S” on the wheel. We will see in a later slide that these six colors can be mixed in proportions to create an entire spectrum of colors.

On the bottom right, we present the concept of complimentary colors. Notice that the complementary color for each primary color is located directly across from it on the color wheel. Thus, each primary color has a complementary secondary color: yellow has purple, red has green, and blue has orange.

Complementary colors are important. As the name suggests, a complimentary color pair has a pleasing feel, and combinations of primary and secondary colors are therefore used for corporate logos:

The above logos, from left to right, are for Google Chrome, MacDonald’s, Apple, and NBC. Notice that the Apple logo closely mimics the visual spectrum, and the NBC logo uses all six primary colors and their complementary ones.

We will discuss another important use of complementary colors on the next slide.

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One useful feature of secondary or complementary colors is that one can use a primary color’s complement to add shading, increasing the depth and three-dimensionality of a painting.

In this example, a two-dimensional blue circle is shaded with its complementary orange color. This produces a natural shading effect that adds structure to the circle, converting it into an illusion of a three-dimensional sphere ball. One might think you would shade an object simply by darkening the color with black paint. This suggests that all shadows are black—they are not. 

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Color is frequently used in painting to portray distance. Look at the photograph on this slide. One can readily notice two things. First, objects closer to the viewer have greater detail. As the scene moves further from the observer, detail is lost to the point that very little detail is apparent as the picture approaches the horizon. 

The second important observation to make when examining this slide involves yet another property of color—color temperature – its warmth or coolness. We will discuss the use of warm and cool colors in the next few slides. 

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We begin by looking at one of the most recognizable paintings in Western art history: the Mona Lisa by Leonardo da Vinci (pictured on the left). The master painted it in the early sixteenth century (1500s). The painting itself is discussed further on the following slide.

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When great distance is represented, there is usually a loss of sharp details as the perceived distance from the foreground increases. That is, less detail is seen the further away an object appears in a painting.

One sees that the detail is greatest on the model herself. From there, detail is lost as the eye looks further or “deeper” into the background landscape. 

Finally, one can clearly see (labeled on the far right of the slide) how receding distances are portrayed with cooler colors. This occurs from the warm browns and oranges of Mona Lisa, which is also carried somewhat into the landscape closest to us. As the landscape recedes, the warm colors are gradually replaced by the much cooler greens and blues of the distant horizon.

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This slide once again presents the color wheel. In this case, the secondary colors are expanded by mixing different proportions of the two primary colors that they are located between. Thus, the orange closest to the primary color, red, is “redder” than the orange closer to its other primary color, yellow. Thus, the orange nearest the primary yellow is “yellower” than the other oranges in the sequence. The same applies to the colors between red and blue and between blue and yellow. 

Color warmth is indicated on the outer perimeter of the wheel. We will see how color warmth is used for emotional effect in the next several slides of paintings by the Dutch post-impressionist painter Vincent van Gogh.

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This is the first of three examples of how the artist Vincent Van Gogh used warm and cool colors to set the mood of four different paintings.

This first example was painted in 1888 and is entitled Summer Evening Wheatfield with Setting Sun. The majority of the painting (the wheatfield) is rendered in warm yellows, browns, and reds. Notice that, in the distance, cooler colors like blues and greens are used. Using warm colors in the foreground and progressively cooler colors in the distance is a very common method to portray depth and distance.

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This Van Gogh painting, Starry Night Over The Rhone, also painted in 1888, has an entirely different atmosphere from the Wheatfield painting on the previous slide because it has a predominantly cool palette. The blues and blue/grays suggest an overall mood of quiet and calm.

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Finally, both of the paintings on this slide are self-portraits of Van Gogh, both of which were painted in 1889. Notice the completely different moods of the two paintings. Key color samples from both paintings were selected and shown in boxes at the bottom of the paintings. 

This side-by-side comparison highlights the visual impact of color warmth.

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We now turn to the Investigation 5 Lab. In the lab, students will use the Go Direct SpectroVis Plus spectrophotometer. You will begin with solutions of the three primary colors: red, blue, and yellow. The solutions contain water and food color, which contains color pigments. Obviously, the pigments in food color are nontoxic. This is not the case with other art pigments, like oil paints, for example. Such pigments may contain any number of toxic substances, minerals, and metals.

Students will conduct an absorption scan of each color sample. Remember that the color that an object appears to us – in this case, the colored water samples – is the color that IS NOT absorbed by the sample. We can only perceive the light that is reflected from a sample, not the light that is absorbed. Keep this in mind as you interpret your results.

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After doing an absorption spectrum on the three primary colors, students will mix the samples to create the secondary complementary colors green, violet, and orange. These colors will also be analyzed by performing an absorption spectra on each. 

Students must appreciate that we can only see colors of light that are reflected by pigments and not those that are absorbed. The pigment chlorophyll, for example, makes plants appear green. This means that the pigment absorbs in most of the visible range of colors but does not absorb in the green region.