Activity: How does a Picture Develop on Photo-paper?

Optics: Expose Photo-paper / Develop Pictures 

Target group: children of 5 to 6 years in kindergarten

Aim: Discover the principle of exposing photo-paper, develop pictures

Where? A group-area that can be blacked out; a photo laboratory

How long? Approx. 2 hours

What? Distinguish photo-paper from „normal“ paper, expose photo-paper, develop pictures

Preparation:

Material: different items, for example scissors, coins, building blocks, cut-out patterns (like stars, fir-trees etc), photo-paper, a torch, three plastic-bowls, developer liquid, water with some vinegar, fixer liquid, clothes line, clothes pins

Steps:

The children tell the difference between photo-paper and normal paper by touching and feeling the surfaces (information #1).

In the dark photo-lab, the children put different objects on the coated side of the photo-paper, (information #2).

The children expose their photo-paper one after the other for approx. 20 – 30 seconds (information #3).

Afterwards, the exposed photo-paper is fastened to a clothes pin and put into the three plastic-bowls, one after the other. First into the developer, then into water for rinsing and finally into the fixer.

Since your skin should not come in contact with the chemicals, the photo-paper is fastened to the clothes pin. When putting the paper into the respective baths, the photo-paper is steadily and easily waved back and forth, (information #4).

The photo-paper (the pictures of the items), are hung up to dry on a clothes line.

The „photos“ thus made are displayed or used for decoration.

Scientific Explanation:

Information 1: The photo-paper has a special, coated surface, that contains substances which are sensitive to light.

Information 2: Since photo-paper is photosensitive, we can only make pictures in dark rooms.

Information 3: The exposure causes a chemical reaction on the spots of the paper that are not covered.

Information 4: A chemical reaction makes the exposed spots on the photo-paper turn dark and almost black depending on the length of the bath in the developer. In the water bath, the photo-paper is rinsed, and in the subsequent bath in the fixer it is made durable.

Possible Variations:

The room is not blacked out. The entire photo-paper turns black.

Instead of different items, developed films are used. What you get are contact prints.

Attention!

The developer and the fixer are damaging to your health! In case of contact with skin rinse the liquids off immediately with cold water.

After use the developer and fixer should be poured into separate containers and kept for re-use.

The remaining used liquids should not be poured down drains (ie toilets or sinks), but must be disposed of by an expert.

Sources: