Investigation 3 Week 3
Dyes contain chemicals that can cause colour changes by reacting and
combining with other chemicals that are either in the dye solution or in the
textile to be dyed.
A dye can cause permanent or temporary colour changes.
When the colour change is temporary, a physical change has occurred.
When the colour change is permanent, a chemical change has occurred.
The various mordants work more effectively with particular types of dye and textiles.
The properties of specific fibres mean they “take” dyes in particular ways: for
example, natural fibres are hydrophilic (water-loving) and therefore absorb waterbased
dyes well. Before students carry out Activity 2, tell them that they are going to
find out how to make the dye stick to the fabric. Explain that a mordant is a
chemical that can be used to help this process.