GAM Products, Inc.
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3.5 Minute Pattern
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Image A Socket
B Lamp
C Reflector
D Gate
E Framing Shutters
F Pattern Holder
G Focal Point - Rays of reflected light converge here
H Plano Convex Lenses
I Lens Focusing Knob
J Color Frame Holder

 

Extending Pattern Life

FIXTURE DESIGN
Stainless steel patterns warp and burn from the concentration of heat on the surface. This concentration at the gate is inherent in the optical design of the ellipsoidal spotlight. Some fixtures are designed 'hotter' than others and therefore are harder on the patterns used in them. A high wattage lamp is harder on the pattern than a low one. There are new cool beam spotlights such as the Altman Shakespeare and the ETC Source Four.

LAMP ALIGNMENT
Lamp alignment is the single most important factor in extending pattern life. When using ellipsoidal spotlights to light actors, we often adjust the lamp to produce a hot center and a feathered edge. When using the same lamp to project a pattern, it is preferable to back the lamp out of the reflector until the field is even all the way across, with no 'hot spot'. With a even field the heat is distributed over the whole surface of the pattern design, rather than one part. In addition, the even field allows more uniform focus.

Most ellipsoidals have thumb screws and/or knobs and socket mounting plates to align the lamps. First, center the lamp filament in the field of light. Then adjust penetration into the reflector. Consult your fixture manufacturer's instructions for more details. It is easiest to align a lamp when it is down on dimmer and the fixture is focused on a flat white surface.

STRESS, COOLING & REMOVAL
Pattern life will vary according to use. If a pattern is 'on' for a prolonged period, it will last longer than one which is stressed by frequent switching on and off. By the same token, a pattern will last longer if it is allowed to cool more slowly in the fixture.

When removing the pattern, be careful not to tear the design by scraping it against the fixture housing. Experience has taught us that many patterns are damaged long before the end of their useful life by being roughly pulled out of fixtures.

PATTERN HOLDER
The pattern holder is important. The best type is the 'sandwich style' holder, which grips the pattern firmly all around the design and aids in heat dissipation. The faster heat is drawn away from the pattern, the longer it will last. The sandwich style holder also precludes accidental dropping of the pattern into the gate of the fixture during insertion and removal. It aids in maintaining uniform focus. Sandwich style pattern holders are available from The Great American Market.

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TRIMMING
When a pattern must be trimmed to fit the pattern holder, it is important to leave as much 'meat' as possible so that the heat will be distributed over as large an area as possible.

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PATTERN DESIGN
Some patterns last longer than others due to the pattern designs. A pattern with thin, delicate lines is more vulnerable than average to burning. A pattern with mostly steel and few holes will warp more readily than one which allows some of the heat to pass through the surface.

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The most durable is a pattern with a 50/50 ratio of steel to holes and an even balance throughout the design. Most of the time, designers choose patterns for looks rather than long life.

Sometimes a 'used' pattern is better than a new one if it has been properly cared for. A warped cloud, for instance, will focus unevenly and look more realistic than a flat one.

PATTERN QUALITY
The first step in extending the life of your patterns, however, is starting out with the best possible patterns. This means patterns manufactured with highly heat resistant steel. Beyond a certain point, the composition of the steel is more important than the thickness. The etching quality of the pattern is equally important. The holes in the design should have clean, smooth straight-walled edges. Lines should be solid, not chewed up. The design area should be free of nicks and scratches.

Certain heat resistant steels are not suitable for pattern production because the molecular structure prohibits the clean etching that is required. The GAMPRODUCT Design Department has an ongoing research program to insure that the best possible materials, both steel and chemicals, and the best possible etching equipment are used in the manufacture of Great American Patterns.

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