Table 2. Microscale Surface Texture Parameters^a in Pristine and Engineered Hair Data.

hair sample	Sq/μm	Sz/μm	Ssk	Sku	Sal/μm	Str	Sdr/%
untreated	0.87 ± 0.19	6.17 ± 1.41	–0.66 ± 0.29	2.93 ± 0.41	5.56 ± 0.69	0.1 ± 0.01	0.54 ± 0.22
treated by keratin (60 min)	1.53 ± 0.32	9.85 ± 1.31	–0.80 ± 0.26	3.08 ± 0.36	4.76 ± 0.53	0.086 ± 0.009	2.68 ± 2.98
treated by halloysite/keratin (15 min)	1.30 ± 0.29	9.68 ± 2.34	–0.79 ± 0.27	3.30 ± 0.37	4.96 ± 0.42	0.089 ± 0.008	4.18 ± 2.2
treated by halloysite/keratin (60 min)	1.33 ± 0.33	9.44 ± 1.61	–0.63 ± 0.28	2.90 ± 0.45	4.58 ± 0.39	0.083 ± 0.007	5.60 ± 2.19

^aSq (root mean square height); Sz (maximum height); Ssk (skewness); Sku (kurtosis); Sal (autocorrelation length); Str (texture aspect ratio); Sdr (developed interfacial area ratio).