"Chemistry of printing: Cyanotyping" experiment
How to make a print on a T-shirt
Did you know that you can make a print on a T-shirt using chemistry? Here’s an entertaining experiment which allows you to print a picture using light and a photochemical mixture.
Safety precautions
Wear gloves when conducting this experiment
Reagents and equipment:
- citric acid (10 g);
- iron (III)-ammonium sulfate (22 g);
- ammonia solution 3% (40 ml);
- solution of potassium ferricyanide (potassium hexacyanoferrate (III) (60 ml);
- glass bowl;
- 4 beakers;
- T-shirt;
- stencil;
- roller or brush;
- lamp.
Step-by-step instructions
To make the print on the T-shirt, first prepare the stencil. Make a negative of the picture that will be printed on the T-shirt. Print this negative on transparent film. Or you can use the instructions from MEL Science: how to make a stencil on electronic media.
Now prepare the light-sensitive mixture: mix the citric acid and the iron(III)-ammonium sulfate, add the 3% ammonia solution and mix. Dim the light and add the solution of potassium ferricyanide. The resulting mixture must be stored in a dark place to avoid exposure to light.
Then take the T-shirt and apply the mixture in an even layer. Cover the soaked area with a stencil and shine the lamp on it. After an hour, remove the stencil and rinse the picture in cold water to remove the remains of the mixture. On the T-shirt we observe a blue print of the picture from the stencil.
Processes description
Under the impact of light, citric acid reduces iron(III) in ferric ammonium sulfate to iron(II). Iron(II) reacts with potassium ferricyanide, forming a bluish pigment – Berlin blue. Important: only wish the T-shirt with neutral detergents.
