What makes dyes used with harakeke change colour? Levels 3 and 4
To understand that when dyes are mixed with different substances they result in either permanent or reversible changes in colour.
Why does hīnau dye turn black?
What makes tanekaha dye turn red-brown?
Tanekaha turns reddish brown when rubbed with ash. This is because the ash contains potassium carbonate which causes the dye to change colour. Potassium carbonate is a base, which is the opposite of an acid. When acids and bases are mixed, they cancel each other out and are no longer reactive.
The reddish brown tanekaha dye can be changed back to brown by adding acid.