Activity 3.7 - Keeping textiles clean

Students learn that washing detergents, composed of certain chemicals, interact on a molecular level with certain fibres (and therefore also with textiles made of these fibres). In order to do this, students also analyze detergents in regard to their chemical composition.

• information material, such as textile care symbols and instructions
• experiments investigating what happens when care instructions are not followed

Experiments:

• Worksheet 8: Research project
• Worksheet 9: How bleaching agents work
• Worksheet 10: The development of laundry detergents – from laboratory to production scale
• Worksheet 11: Behaviour of fibres during washing process 

• This activity (esp. Worksheet 10) can be complemented with an industrial visit (e.g. Henkel AG & Co. KGaA). There further questions can be researched, such as how the components of laundry powder are evenly mixed or how the powder is kept dry during storage.
• For motivation purposes, in the series of experiments investigating what happens when care instructions are not followed, the students can develop their own ideas how to set up experiments testing those properties taking into account comparability and generalizability of their experiments.
• The experiment in D: Students may bring different detergents from home as well as fibre samples from old clothes they do not need any longer if there are no samples at school. Instead of using beakers, students can use yoghurt cups but they cannot be heated!
• Students may work in teams of two: every team gets every type of sample fibre and tests their interaction with one detergent. They should prepare two differently concentrated solutions of their detergent.
• Finally, students present their observations. They might use a camera to keep records of their findings.
• This activity lends itself to going beyond the visible observations and taking into account the chemical structures of different fibres and the interactions between chemical structure and laundry detergent.

Henkel (2008): Sustainable washing for a clean environment – Chemistry for advanced classes (14 – 18 year old). Access to complete unit at http://www.henkel.com/com/content_data/106612_4.8.2_Sustainable_washing_for_a_clean_environment_Chemistry_for_Advanced.pdf.