AIEL Instructional
COLOUR MEDIA
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Colour media is the blanket term for that which is placed
into a light beam in order to tint, or colour-correct it.
Other related products which do not colour the beam are
also included under the term "Colour Media".
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The most popular form is the flexible, transparent Polyester sheet. Usually referred to as "gel", this term comes from the word "gelatin" - a similar, but different and older variety of colour media. |
THE FOLLOWING MAY NOT BE REPRODUCED
WITHOUT PERMISSION FROM THE AUTHOR ©
In earlier times, colour was imparted to stage productions during the day by holding them at different times outdoors so as to take advantage of, and make use of, naturally lit conditions. Warmer colours occur at the start and end of daylight. Brighter ones are seen in the middle of the day, especially under a cloudless sky. To contrast, cloudy skies presented muted colours and a softer, diffused ambience.
At night, candles or torches were typically used, although fireplaces and bonfires would not have been out of the question. Any could impart upon a performance much warmer tones, and induce a heightened contrast against a night sky. Under a full moon though, one could additionally produce a contrast between cold moonlight and warm open-flame sources. In later centuries, coal-oil and gas lamps were used as light sources until the time of electric light.
A way of tinting light at night was through the use of coloured, translucent scarves or handkerchiefs. They would be suspended near the open-flame light source so as to impart colour to the light. Fires were a hazard, but the colours initially served a purpose for a mostly illiterate population. How? By matching the colour of a scene to its emotion, it helped those that were less literate to understand at least the general gist of a play.
Colours might represent:
These were not universally-used combinations, but give an idea of how an entire audience, regardless of pedigree or education, might enjoy and understand a performance. This is little different from today where commerciality must be a viable goal for any organisation or performance business - regardless of how extreme its productions become.
Surprisingly from our technological vantage point, a creative person
centuries ago was able to light a performance, but shone even more
skilfully by taking advantage of some or most of the above. Even the
changing alignment of the stars, moon and planets could conceivably
have been incorporated for late evening, night, or early morning shows.
In later times, coloured glass was used to tint light. By imparting various chemical compounds in the glass-making process, it was possible to colour the glass. As well, the stained glass process used in churches for hundreds of years was incorporated. This was safer than using coloured fabrics, but the glass would eventually smoke over and would have to be cleaned or replaced from time to time.
GELATIN
This was one of the first synthetic colour media devised. It used gelatin (yes, the same as you might eat for dessert). Gelatin is easily dyed and rolled into sheets. When dry, it forms a transparent, coloured sheet that is suitable for stage lighting in non-wet locations and using low-wattage fixtures. The advantages to this type are low cost and a resistance to scratching. (Scratches seem to almost fill in, with this type of colour media.) However, it absorbs moisture and will actually dissolve in water. As well, it becomes brittle after being subjected to stage light beams, and it will tear starting almost from after its first usage, if roughly handled. It is OK for permanent installations where the gel is to be left untouched after being placed, but it cannot stand up well to the abuse of touring.
Gelatin had a good range of colours available but has now fallen into disuse because better materials have emerged that are waterproof and can stand higher heat. There is no known manufacturer currently producing the gelatin colour medium.
ACETATE
Acetate was the original waterproof, plastic colour media. It is capable of withstanding temperatures of around 100 C, is tougher than Gelatin, and as said, is waterproof. However, it's prone to fading and if subjected to multiple high-heat/cool cycles becomes brittle and will tear or shatter. It scratches easily, as well. The colour range is at least as good as Gelatin. As regarding gelatin, there is likely no manufacturer making an acetate colour medium.
POLYESTER
Here was the next material successfully used. It can withstand temperatures of 200 C, and is waterproof and resistant to fading in all but the hottest fixtures. This was the colour medium that saw the theatrical colour range expand greatly so that today, there are hundreds of shades available.
POLYCARBONATE
The latest of the plastic colour media materials, it is very strong, fade resistant and can handle temperatures around 400 C. Colour range compares with that of the Polyester medium.
Polycarbonate crinkles and can become brittle after prolonged exposure to high heat. However, it remains fairly robust, unlike Gelatin. When the latter becomes brittle, it tears easily. Polycarbonate can be broken in this condition, but it takes more effort. If handled carefully, one can continue to use the gel until it becomes too dark to be usable. (Unlike Acetate and Polyester colours which lighten with usage, Polycarbonate filters actually darken during their service life.)
GLASS
As mentioned, coloured glass had been around for centuries, but after the coming of electric light and gelatin, it saw only limited stage usage except in border lights and some low to medium wattage fixtures. Today, it may still be found, but these uses have been mostly supplanted by plastic colour media, and now by coloured LEDs which require no filters because they emit light at given wavelengths, thus actually shining in a given colour.
However, one major location seen now is in moving beam and colour-changer fixtures in the form of dichroic glass filters. This is heat-resistant glass that has a thin coating which diffracts the light into pure colours in much the way as does a rainbow or as seen in an oil slick on water. This results in very narrow-range colour with a high transmittance factor. These filters are available outside of moving beam/light usage but have not proven popular due to their high cost and limited colours.
On a related subject, another instructional
available at this website discusses
Primary and Secondary Colours.
Here is the AIEL Purchase Guide's
Colour Media Table,
a summary chart of the types just discussed.
You can obtain a Swatch Book
of samples
of the Polyester and Polycarbonate ranges.
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