POTTERY PRODUCTION PRACTICES: Harnessing the Power of Air
February 2, 2006
Air release dies allow for greater production quantities and often a more consistent quality, with longer-lasting tooling and considerably less tooling inventory than more traditional clay forming methods.
Plasters are synonymous with clay processing, both for their water absorption and self-cleaning properties. Most tooling for clay products is based on the premise that the ability of plasters to absorb water depends on the porosity of the plaster being used, coupled with the point of saturation where the plaster will no longer absorb efficiently. Plasters and cementious material hybrids have been formulated for greater compressive strength and resistance to abrasive wear than the traditional plasters, but they often lack porosity.
Though not limited to cementious plaster hybrids, air release die and mold fabrication processes have been developed to open microscopic passageways and allow for clay tooling to absorb water from the clay being processed. Compressed air can then be forced through the same passageways to purge the tooling of moisture for continuous production. The air moving over the water causes a hydraulic action against the clay surface, and the newly formed part releases from the die or mold for a quick production turnaround without having to wait on the more traditional plaster tooling to draw enough water from the clay body to cause the clay to shrink away from the form.
Air release dies allow for a greater production quantity and often a more consistent quality, with longer-lasting tooling and considerably less tooling inventory than the more traditional clay forming methods. As a result, pottery producers can save on valuable floor and storage space, setup time, and financial investment.
Tooling DesignAir release tooling can be most effective with die pressing, jigger-jolly forming, double-wall gravity slip casting and pressure casting, and the cost of such tooling is equally practical for larger production plants and small production studios. The technology can provide a welcome solution for studio potters who have reached the inevitable bottleneck in the quantity of handmade products they can produce without sacrificing the quality and originality they and their customers have come to expect, but it can also be used by large-scale manufacturers producing technical parts. The tooling can be produced internally or can be outsourced to experienced toolers, thereby allowing the manufacturing plant or studio potter to focus on what they do best without taking away from the creative expression of the artist's original work or the engineers' intent.
The typical air release press die, jigger-jolly form or slip casting mold contains an introductory air passage molduct tubing system that is cast in the tooling matrix. The molduct tubing used can vary in diameter to match the size of the project. The introductory air passage layout consists of a hollow braided rope tied to a wire positioning grid and laid in a configuration for an even dispersal of air throughout the tooling. Air release press dies and jigger forms are usually cast in metal retainer rings that have mounting lugs, registration pins and control stops to maintain the proper alignment and distance between the matching halves of the setup.
Air release tooling can allow for many different part configurations and applications of aesthetic art tiles, plaques, bowls, lids, saucers, sprigs and handles. It affords the production of repeatable high-temperature refractory slump molds for slumping glass pattern work or other kiln furniture, to industrial components for electrical switch plate covers and insulator components, to specialized ceramic dies for extruding metal profiles, refractory containments for metal castings and other specialized metal or powdered metal matrix processing.
A Pressing SolutionWhile air release tooling can be used with a variety of forming techniques, it has also been designed into a relatively new press that is a rescaled adaptation of a conventional ceramic press.1 The press has a small footprint and was developed to fit into an existing studio or production line with minimal downtime. The system allows pottery producers to create bowl and platter profiles without having to invest in a large conventional press and expensive tooling that would otherwise be required to quickly and easily form these pieces.
William Melstrom of Spiral Studio in Austin, Texas, was one of the first potters to use the new press. The producer of functional porcelain pottery is best known for his exacting work with crystalline glazes. However, as a small business owner, Melstrom often feels the time crunch faced by many pottery producers. "Less than 50% of my time is spent actually making pottery," he says. "The rest of my time is devoted to marketing, bookkeeping and other business-related endeavors. When I'm making my pottery, I want to focus on the firing and glazing processes, rather than on forming."
To save time, Melstrom began outsourcing his forms to other potters-an expensive solution. When he saw an ad for the air release press in a trade magazine, he immediately purchased one for his studio. "I still throw the majority of my work, but I use three air release dies for some of my bowls. The press is unbelievably fast; it's amazing how many pieces one person can produce on this machine. Using the air release press lets me save a significant amount of time and money," he says.
Linda Taylor of Clay-Earth Studios in Minneapolis, Minn., has had a similar experience. After an accident prevented her from throwing her sculpted and carved functional pieces, Taylor purchased an air release press in 2004. "The equipment benefits include the clean, quick release of forms with minimum of distortion; the ability to reuse scrap clay with minimum of kneading; and the easy creation of multiples of a form that I have designed and can then finish by carving," she says.
As pottery producers look for new ways to enhance their productivity and design capabilities, air release technology is providing a powerful solution.