The kit consists of a number of sets of film positives and negatives that, when viewed together in the correct fashion on a light table, demonstrate some little known and interesting properties of moiré patterns. All the pieces of film, or screens, are contact prints on high contrast lith film, exposed one at a time and processed by hand. The kit also includes a 72 page book (PDF format) on CD entitled Mastering Moirés: Investigating Some of the Fascinating Properties of Interference Patterns, which details some of the science behind the phenomena demonstrated by the screens. Below is a brief description of each set of screens and the of the effects they produce.

Screen tints are rectilinear arrays of dots on film, which are (or were, before the advent of direct-to-plate technologies) in common use at most commercial printing establishments. They are commonly identified in terms of percent, that is, in terms of the amount of available light they are capable of transmitting. Thus a 20% screen tint has dots in the form of openings that allow 20% of the light to pass. The moiré patterns they are capable of generating are very simple, similar in structure to the screens themselves, and yet very dramatic. Minimizing their effect has been the goal of much research done over the past century. The patterns can also graphically demonstrate some interesting geometrical phenomena, such as the existence of the so-called Pythagorean triplets. Also, when one of the interacting screens has very small openings (as for instance, a 5% tint), the pattern seems to mirror the fine structure of the other screen. For example, the pattern produced by the interaction of a 5% tint and a 20% tint resembles a much enlarged version of the 20% tint. This effect hints that other imaging effects are possible.

There are four 5" x 7" screens in the set: 5%, 20%, 50%, and 70%.

Screen Tint Angle Indicator/Graphical Data Encoder

Since the overall structures of moiré patterns mimic the structures of the interacting screens, but on a much larger scale, the patterns provide a way to make visible data encoded into the structure of one of the interacting screens. A practical application for this technique was the development of the screen tint angle indicator: a device to be used to determine the proper angles at which to place the screen tints used in multi-color printing. When a simple screen tint is placed over this device and rotated, the name of each of the colors used in the four-color process (cyan, magenta, yellow, and black) appear in sequence within a moiré pattern. The precise angle for the particular color is indicated when the pattern reaches its greatest extent. The device may be used to encode any type of graphical data, as long as it is black and white and has large enough detail, relative to the screen's dot structure. Any of the four screen tints included in this kit will create the effect if used in combination with one of these devices. However, the 20% tint probably creates the optimal effect.

This set contains two 5" x 7" screens: the screen tint angle indicator and an encoding of images and text from the Rosetta Stone.

Imaging Screens Composed of Typewritten Characters

The effect evident in the pattern created by the interaction a 5% tint with a 20% tint (as described in the text on screen tints) hints at the imaging capabilities of certain types of moiré pattern: when one of the interacting screens has very small openings, it acts as a delineator, with each opening revealing a slightly different area of the corresponding element on the screen below in a very orderly fashion, and thus creating a pattern whose elements resemble (on a much larger scale) those of the second screen. A simple way to test whether or not the effect extends to more complicated forms of imagery is to create a pair of custom screens: a delineator or reference screen, composed of an array of very small openings; and an image screen, composed by repeating a simple graphic character in a similar array. The easiest way to do this is to use a typewriter or word processor, with monospaced type, to fill one sheet of paper with repeated periods, and another sheet with a repeated letter, say a capital 'F.' Photographic negatives, on high contrast lith film, of these two sheets of paper, are the reference screen/image screen pair we seek. When they are viewed together on a light table, a pattern appears that is indeed an enlarged version of repetitions of the letter 'F.'

This set contains three 5" x 7" screens: a negative of repeated periods; a negative of repeated 'F's; and a negative '1's and '0's, separate and in transition.

Rectilinear Array Reference and Image Screens

The basic idea behind the set of screens created with typewritten characters can be implemented with a little more sophistication by employing graphics software now available. Both the reference screen and the image screens can be created by stepping and repeating simple images (dots in the case of the reference screen), producing rectilinear arrays over as large an area as we please within the virtual space of a drawing program. The files can then be output as film negatives to yield the screens. It should be noted that other types of array, like hexagonal configurations, work just as well, and their overall structures will be mirrored in the way that the repeated pattern images are arrayed.

This set contains three 5" x 7" screens: one reference screen and two image screens.

Random Array Reference and Image Screens

Is it possible to create a moiré image that does not repeat? Since the overall structure of a moiré pattern reflects the structures of the interacting screens, would not a set of screens composed of random but matching, arrays of elements give rise to a single pattern image? Creating such a pair of screens calls for a little more ingenuity, but with drafting software with built-in programming capabilities, it is not so very difficult. Again, the results can be output directly to film to create the screens. The randomly arrayed reference and image screens do indeed give rise to a single pattern image, which can be made to enlarge and reduce and move about over the entire surface of the combined screens. The images on the image screen can even be made of such a size that they overlap and obscure each other, but the pattern image will still emerge intact.

There are three 5" x 7" screens in this set: one reference screen and two image screens.

Linear Array Reference and Image Screens

Other types of moiré pattern image are possible. One interesting type is created by using a reference screen consisting of vertical slits rather than pinhole-like openings, and an image screen consisting of a row of extremely elongated images. When you place these two screens together, pattern images emerge that are undistorted, enlarged copies of the original distorted images. This type of screen combination allows more light to be transmitted and also makes possible a pattern image having much more detail. It should be noted that all the different types of reference screen/image screen sets can be used out-of-contact with each other, as by placing a sheet of glass or clear acrylic between them, to give rise to pattern images with apparent three-dimensionality. Since their pattern images are the brightest and the most detailed, linear reference screen/image screen pairs work best for this effect.

There are five 5" x 7" screens in this set: one reference screen and four image screens.

Floating Moiré Grid Screens

Another interesting property of moiré patterns is their ability to produce the illusion of three-dimensionality. If, instead of placing two screens in contact with each other, we separate them by a small amount, the pattern that emerges appears to float in space. By controlling the relative spacing of elements on the two screens and the distance between them, we can make the pattern appear to lie on any plane we like, either above or below the screens.

If the two screens in this set are placed on a light table with the positive screen on top, and they are separated by a small amount, for instance by placing a flat object like a coin between them, the pattern will appear to float above the pair of screens. The pattern's topology will clearly be seen as being influenced by the separating objects.

This set consists of two 7" x 10" screens in the form of grids, one positive and one negative, with slightly different line spacings

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