Heat-Treated Wood as a Substrate for Coatings, Weathering of Heat-Treated Wood, and Coating Performance on Heat-Treated Wood

Table 2

Comparison of surface free energy of heat-treated (HT) and untreated wood samples.

LW-AB approach
Substrate	γ^LW	γ^AB	γ^+	γ^−	γtot	Temperature (°C)	Heat treatment	Reference
Beech untreated	49.5	9.1	1.5	13.5	58.6			[28]
Pine untreated	46.4	8.2	1.1	15.8	54.8
Beech HT	50.9	5	2.3	2.7	55.8	240	Treatment under nitrogen
Pine HT	50.7	1.5	0.8	0.7	52.2	240
OWRK approach
Substrate					γS	Temperature (°C)	Heat treatment	Reference
Beech untreated	38.7		13.9		52.6			[25]
Beech HT	39.9		6.8		46.7	190	Treatment under vapor
Beech HT	46.3		2.6		48.9	212
Spruce untreated	53.4		0.97		54.4			[35]
Spruce HT	59.6		0.04		59.7	210	Vacuum treatment
Poplar untreated	34.98		8.07		43.05
Poplar HT	36.99		3.77		40.76	160	Treatment under vapor	[36]
Poplar HT	36.31		4.35		40.66	180
Poplar HT	37.63		1.67		39.31	200
Poplar HT	37.55		1.13		38.68	220
European ash untreated	43.94		6.74		50.68
European ash HT	52.19		0.1		52.2	192	Treatment under vapor	[20]
European ash HT	52.61		0.1		52.62	202
European ash HT	51.58		0.1		51.59	212