Teaching Materials - Exercise

Silver halide experiment

Name of Artist Educator: Ho Man Kei, Vik Lai
Level:
Excercise Category: Technical exercise

Images are easy to be obtained but hard to be preserved.


Concept / Inspiration:

Images are easy to be obtained but hard to be preserved.

Many years ago, people found that light could pass through a small hole and get into the dark room. The light could project the objects from the outside onto the wall up-side down. This is the predecessor of camera – Camera Obsura. At that time, people were able to produce image although they could not preserve it. Nicéphore Niépce used bitumen and tin-lead alloy to make the first preservable image. Later, Louis Daguerre optimized it and created daguerreotype. Image could finally be able to retain on touchable media.
The exercise starts from the history of photography in order to let the students to understand the principles of making of and finalization of images.


Goals:

To let students understand the principle of photography, treasure the images more, and get to know the black and white photography and film photography.


Materials / Equipment:

  • Silver nitrate (2g)
  • Diluted water (25 mL)

(quantity of the above two should be adjusted according to the recommended ratio)

  • Drawing paper
  • Cotton ball
  • Forceps
  • Light-proof envelop
  • Leaves/ stone/objects that are transparent or non-transparent
  • Hair dryer

Location:

Indoor environment with low light level, outdoor environment with plenty of sunlight


Workshop Description:

  1. First of all, mix 2g of silver nitrate with 25mL of diluted water in an indoor environment.
  2. Dip the solution with a cotton ball and wipe it on a piece of drawing Use hair dryer to dry the paper and place it in a light-proof envelop.
  3. Go to somewhere with sunlight, take out the piece of paper from the envelop and place it on the ground.
  4. “Silver halide” is an element that is rather sensitive to light. Students are required to swiftly place the grass, stones and leaves that are randomly picked from the ground onto the drawing paper and undergo the process of exposure. Silver nitrate would turn the surface of the paper from white to reddish brown under the sunlight.
  5. Remove the objects from the paper. As part of the paper is covered by the objects and not exposed to the sun,, different shapes of white “shadows ”would be found on the paper, i.e. stones, leaves, grass.
  6. Wash out the chemicals on the paper. Let it dry.

Note 1: If the objects are removed from the drawing paper and the paper is left under the sunlight for a while, the paper would go all black. The traces left by the objects would disappear. This process is quite interesting in the sense that student could witness the process of image disappearing.


Expected Outcome:

The process would allow people witness how nature depicts an image by itself. It is simple but impressive. Nowadays, many people use digital camera and shoot with shutter speed. It is easy to neglect the way to appreciate the photographs. Students are expected to find the nature of the photo shooting and to enjoy the development and formation of the image. It is significant to focus the delicacy of the image.


Actual Outcome:

During Class﹕

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Work:

1
2
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Student Feedback:

“Understanding the photography development is a good experience to me.”


Reference Materials:

The History of Photography : from 1839 to the present
by Newhall, Beaumont (1908-1993)