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Automatic Stencil Developing

(May 2002) posted on Mon Jun 03, 2002

The authors explain how automatic developers work and compaire their performance to manual developing methods.

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By Carol Swift, Peter Kiddell

Automatic stencil-developing technology has become increasingly common in screen-printing operations, and many businesses that haven't already added such systems are beginning to give developing equipment serious consideration. An automatic developing system works much like an automatic screen washer. These units, which may be standalone systems or part of conveyorized screenmaking lines, house spray nozzles that deliver a uniform low-pressure wash to remove unexposed emulsion without damaging the stencil image. Automatic stencil-developing systems are available from most screen-printing equipment manufacturers and suppliers.


The traditional, hand-based stencil-developing method may rely on several employees with varying levels of skill who use a garden hose or pressure washer to resolve image areas in the exposed stencil. While hand-developed stencils may be acceptable, they are more likely than those developed automatically to contain inconsistencies that make them flawed or even unusable.


Spray characteristics and stencil quality


In a process where reducing the variables is crucial to success, having screens developed under a controlled pattern of sprayed water is vital, as is using the correct pressure and angle for spraying. These factors are harder to control in manual developing than on automated systems, which is why hand-developed screens are more likely to have inconsistencies and inferior stencil quality. In some cases, however, manual developing may be acceptable, such as when the washed-out image is bold and doesn't require high edge definition.


With fine details and halftone dots, however, the stencil edge quality is much more critical and those responsible for manually developing stencils must be diligent in their work. Hand developing high-resolution stencils takes time and skill, and even the most expert screenmaking technician will struggle to achieve consistent washout results over the entire image area of a screen <B>(Figure 1A)</B>.


With an automated system, however, it's possible to control pressure, angle of flow, speed of traverse, and coverage, while simultaneously washing out both sides of the screen <B>(Figure 1B)</B>. Detail that was almost impossible to develop manually will wash out much more cleanly with an automated developing system. Not until you use an automatic developer for the first time do you realize the quality and consistency that such a system makes possible. And it is not just image quality where these advantages are apparent.


Water recycling



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