# Moire patterns.

Moire Patterns

I was looking for an art project that would be interdisciplinary, showing the crossover of creative thinking between art and other subjects. By chance, I read a book on Op Art which had a short section on moire patterns. I also happened to go to The Exploratorium (a hands-on science museum) in San Francisco and viewed an exhibit of moire patterns. It then occurred to me that the moire pattern could very well illustrate interdisciplinary creative thinking to my students.

The objective of the third component of the Visual Arts Heritage unit of The California Public Schools Art Framework is to "understand that art reflects, records and shapes history and plays a role in every culture." The moire pattern is an example of art's influence and value in other areas.

A moire design is produced when one linear negative and positive pattern is placed over another pattern with negative and positive lines at an angle of 30 degrees or less. Moire patterns can be produced by parallel lines, radiating lines, concentric circles, squares or triangles, dots and spirals. Some of the simplest moire patterns can be produced when one set of parallel lines is superimposed over another set of identical lines. The angles become magnified and appear to fill in. If one of the lines has a tiny displacement, the moire pattern will show a magnified displacement. A sheet covered with parallel lines about one or two centimeters apart placed over a spiral drawn with lines the same distance apart is one example of a moire pattern.

As a combination elementary, junior high and high school art teacher for the Santa Clara court schools, I developed a project that could be used at all three levels. I prepared two sheets to make moire patterns. One was covered with parallel lines drawn with a ruler about 1 1/2 cm apart, and the other was covered with concentric squares about 1 1/2 cm apart.

I began an assignment for the elementary class by asking students how they thought art related to the world around them. I showed them slides of Op Art and moire patterns in Japanese silks. I explained how moire patterns have been used in other fields and how they came to be used by artists. I then distributed acetate sheets covered with parallel lines, some with dots, some with radiating circles and some with concentric circles. I had students move them one in front of the other to see the moire patterns and the illusion of movement.

I demonstrated drawing on the prepared sheets (one with parallel lines and one with concentric squares) -- a spiral with lines as close and even as possible, a square with smaller concentric squares inside and organic shapes. Each student was given the two prepared sheets. They began by experimenting with the designs I had demonstrated, then were encouraged to experiment and discover their own moire designs. The last part of the assignment was to make a finished drawing with the moire patterns they liked most and then to go over the drawing with black felt-tipped pens. The pen will bring out the moire pattern even more. Students then looked at each other's drawings and, for homework, found moire patterns on their television sets, in magazines or around their neighborhoods. I followed up the next day by bringing in rubber stamps of grids, spirals and mazes. The class created more moire patterns by stamping once and then stamping over the design at an angle of less than 30 degrees to get a very exact Op Art moire pattern.

For my junior high and high school students, I followed a similar introduction with an opportunity to practice making their own moire patterns and to get the feel of what a moire pattern is. Their assignment was to make a simple design of their own choosing with repeating lines, spirals, concentric shapes, radiating lines or drawing designs on tracing paper over carbon paper to duplicate the drawing. After completing the drawing, students rotated the copy until they saw a moire pattern emerge. They then taped the drawing in place, traced the bottom drawing onto the top drawing and went over it with black felt-tipped pens for a good moire design. I recommend a simple design first and then more complex designs for the high school project. Students could experiment with filling in areas and using color to create a final moire design. The homework was to find moire patterns in books, magazines, television or in their neighborhood, and the last class was spent making moire patterns with rubber stamps.

Further moire projects can be made three-dimensionally with wood construction, silk screen or linoleum blcoks (moire patterns are created by printing the design twice on one sheet of paper at different angles), ink drawings and using the potter's wheel to create concentric moire designs. Students can also make their own line pattern stamps using clay, Styrofoam or potatoes for the stamp, and then print them twice at different angles on-clay or paper.

Uses of moire patterns

The word moire (mwah ray) is French for "watered." The Japanese used moire patterns in their watered silks to produce a pattern resembling the shimmering surface of water. As long ago as 1874, British physicist Lord Rawleigh was using moire patterns in science to see the perfection of ruled diffraction gratings. A May 1963 article in Scientific American by Gerald Oster and Yasunori Nishijima illustrated the use of moire patterns created by a crystal grown on another crystal creating a lensless moire microscope for exact mathematical solutions of the interference of light waves. The article also illustrated the use of the moire design in solving problems of architectural acoustics and designing breakwaters for harbors. This article brough the moire design to artists' attention who began using it in the Op Art produced at that time.

Moire patterns are now being used to detect early signs of sclerosis in children by passing light through a set of vertical parallel lines creating shadows on the back of the child. A healthy back will have a symmetrical moire pattern and a back with sclerosis will have an asymmetrical pattern. In the late nineteenth century, some of the first moving pictures were created by using moire patterns. By slowly moving a sheet of acetate covered with parallel lines over a photograph of a car facing forward you can see how this works.

Moire patterns are present in our environment. You can see them on your television set when the patterns are not aligned or when driving past fences. You can see moire patterns by looking through a double screen door. It's strange how this pattern can be seen in a micrograph of crystals, in the printing process of pictures, in electrostatic fields and mathematical solutions. Art that is abstract can also be representational.

PHOTO : Moire patterns created by superimposing two patterns.

PHOTO : Moire pattern created by elementary student on parallel line sheet.

PHOTO : Moire patterns created with rubber stamps.

Annemarie Baldauf teaches art at the C.W. Washington School, Walnut Creek, California.
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