Table 2. Values of dispersion component, polar component and γ _la for the liquids used at 25 °C (taken from ref. 43) and both the three-phase equilibrium advancing liquid–air contact angles and the oil–water contact angles measured on the surface of disks formed from the pigment particles.

Liquid	Tension/mN m–1			Liquid–air contact angle/°
	γ d la	γ p la	γ la	PR	PO	PY	PG	PB	PI	PV
Water	21.6	50.5	72.1	87	64	108	92	93	80	85
Glycerol	34.0	30.0	64.0	74	44	100	77	79	72	66
Formamide	39.0	19.0	58.0	72	37	83	75	78	53	58
α-Bromonaphthalene	44.4	0.0	44.4	<5	<5	<5	<5	<5	<5	<5
n-Hexadecane	27.8	0.0	27.8	<5	<5	<5	<5	<5	<5	<5

	Oil–water contact angle/°
	PR	PO	PY	PG	PB	PI	PV
Heptane–water (expt.)	143	84	142	144	139	141	143
Heptane–water (calc.)	110	92	146	125	124	112	122