RH simulation model for canvas paintings protected by an aluminium backplate and an additional hygroscopic layer

Heritage Science

Table 3 Summary of results of cases where permeance and infiltration are changed

Case	Permeance (vapour)	Infiltration rate	RH cycle delays to the ideal values at the void layers temperatures			RH interval (max/min) % in 1st cycle
Case	kg m⁻² s⁻¹ Pa⁻¹	nVol/h	Canvas	Cotton	Aluminium	Canvas	Cotton	Aluminium
1	1.00E−12	0.4	0		0	60/59		72/56
1.A	1.00E−09	0.4	1/2		0	60/53		71/50
1.B	1.00E−12	10	1/4		0	60/58		72/55
2	1.00E−12	0.4	1/2	1/4	0	65/52	59/58	60/56
2.A.1	1.00E−11	0.4	7/16	1/4	1/8	65/52	58/60	57/61
2.A.2	1.00E−10	0.4	7/16	1/4	1/8	65/52	58/58.5	56.5/60.5
2.A.3	1.00E−09	0.4	7/16	1/4	1/8	64/50	60/54	61/53
2.B	1.00E−12	10	7/16	1/4	1/16	64/50.5	59/55.5	60/54.5
3	1.00E−12	0.4	3/16		7/16	61/59		72/50
3.A.1	1.00E−11	0.4	3/16		5/16	62/59		73/50
3.A.2	1.00E−10	0.4	3/16		5/16	65/68		74/52
3.A.3	1.00E−09	0.4	2/16		17/32	74/46		72/52
3.B	1.00E−12	10	3/16		5/16	70/49		72/50
4	1.00E−12	0.4	1/4	1/4	1/2	66/61.5	66/61.5	75/54
4.A	1.00E−09	0.4	1/8	1/8	3/8	67/52	67/52	70/53
4.B	1.00E−12	10	3/16	3/16	7/16	65/57	65/57	72/52

The outputs are cycle delays in relation to an ideal case (maximum RH and minimum T coincide) and RH range at different layers. Cases indicated a N, N.A and N.B, where N denotes the original Cases 1–4, A denotes change in permeance, and B denotes change in infiltration rate