**3. Chemical modification**

## **3.1 Bleaching**

Wool bleaching affects the fibre surface, but is not performed specifically to produce functionalised surfaces, so will not be discussed at length in this chapter. Agents utilised in protein-fibre bleaching include hydrogen peroxide, sodium borohydride, sodium bisulfite, thiourea, oxalic acid and blue light (Arifoglu *et al.* 1992; Millington 2005; Yilmazer & Kanik 2009). Bleaching is sometimes combined with additional surface modification techniques such as scale removal (Chen *et al.* 2001).
