Modifying the radiation ratio of tonewoods through wood degradation

Figures & data

Figure 1. Relative change in R due to heat treatment as a function of exposure temperature for different exposure times for pine and spruce. Different letters indicate statistically significant differences.

Table 1. Changes in ρ, c, MOE_Y and R as function of the exposure temperature.

T (°C)	t (h)	Δρ (%)	Δc (%)	ΔMOEsd (%)	ΔR (%)
160	1	−1.22 ± 0.40	−0.76 ± 0.71	−2.71 ± 1.60	0.47 ± 0.67
	2	−1.18 ± 0.54	−1.80 ± 1.65	−4.67 ± 3.44	−0.62 ± 1.54
	6	−1.09 ± 0.55	−1.71 ± 4.07	−6.86 ± 4.30	−0.64 ± 3.63
	8	−1.53 ± 1.74	−2.84 ± 1.38	−7.01 ± 3.58	−1.31 ± 1.85
180	1	−1.13 ± 0.45	−1.74 ± 2.02	−4.51 ± 4.13	−0.62 ± 1.86
	3	−0.87 ± 0.88	−3.02 ± 1.22	−6.75 ± 2.64	−2.16 ± 1.38
	6	−2.34 ± 1.16	−3.63 ± 0.98	−9.28 ± 2.71	−1.32 ± 0.82
	8	−2.25 ± 0.23	−3.28 ± 0.80	−8.56 ± 1.43	−1.05 ± 0.94
200	1	0.01 ± 0.52	−5.60 ± 2.33	−10.84 ± 4.21	−5.60 ± 2.59
	3	−1.04 ± 1.43	−4.44 ± 2.38	−9.56 ± 5.25	−3.44 ± 2.02
	6	−2.44 ± 1.59	−5.54 ± 3.26	−12.81 ± 7.21	−3.20 ± 2.23
	8	−2.57 ± 0.73	−5.74 ± 2.17	−13.37 ± 4.53	−3.26 ± 1.67
230	0.17	−0.09 ± 0.13	−2.52 ± 1.63	−5.04 ± 3.09	−2.42 ± 1.70
	0.5	−1.17 ± 0.31	−2.43 ± 3.73	−5.81 ± 7.30	−1.28 ± 3.68
	1	−3.06 ± 1.58	1.16 ± 0.92	−0.82 ± 1.2	4.38 ± 2.50
	2.5	−3.54 ± 2.24	3.27 ± 0.83	2.90 ± 3.50	7.09 ± 2.17
250	0.08	0.15 ± 0.06	−2.95 ± 1.17	−5.66 ± 2.29	−3.09 ± 1.15
	0.25	0.06 ± 0.41	−1.66 ± 1.41	−3.23 ± 2.57	−1.71 ± 1.67
	0.5	1.70 ± 0.71	0.88 ± 0.79	3.50 ± 1.67	−0.81 ± 1.11
	1	−4.46 ± 0.88	3.21 ± 0.43	1.77 ± 1.17	8.04 ± 1.15

Note: Treatments that reduced ρ and maintained or improved MOE_Y are highlighted.

Figure 2. Relative change in R due to fungal degradation as a function of exposure time (t) for pine and spruce. Different letters indicate statistically significant differences.

Table 2. The average change in ρ, c, MOE_Y and R of pine incubated with brown rot (L. sulphurous) with standard deviations.

t (weeks)	Δρ (%)	Δc (%)	ΔMOEL (%)	ΔR (%)
1	−0.35 ± 0.11	1.03 ± 0.64	1.73 ± 1.33	1.38 ± 0.61
2	−0.53 ± 0.36	−1.17 ± 1.63	−2.81 ± 3.43	−0.65 ± 1.44
6	−1.21 ± 0.08	1.94 ± 0.91	2.67 ± 1.85	3.19 ± 0.90
20	−1.01 ± 0.98	5.43 ± 1.48	10.06 ± 3.40	6.51 ± 1.73

Table 3. The average change in ρ, c, MOE_L and R of pine incubated with white rot (S. commune) with standard deviations.

t (weeks)	Δρ (%)	Δc (%)	ΔMOEL (%)	ΔR (%)
1	−0.38 ± 0.07	2.02 ± 1.24	3.69 ± 2.51	2.41 ± 1.26
2	−0.37 ± 0.08	0.28 ± 1.21	0.2 ± 2.42	0.66 ± 1.24
6	−1.32 ± 0.11	2.61 ± 1.90	3.92 ± 3.76	3.98 ± 2.00
20	−3.50 ± 1.10	7.15 ± 1.78	10.79 ± 3.06	11.05 ± 2.81

Figure 3. Relative change in R as a function of exposure time (t) for sodium treatments.

Table 4. Improvement in R after heat-, fungal- and sodium treatment, as well as combined treatments.

Wood type	Treatment	Exposure time	ΔR (%)
Pine	white rot	6 weeks	3.98 ± 2.00
Pine	white rot + heat	6 weeks, 1 h	13.34 ± 2.80
Pine	0.2 M NaOH	120 h	5.84 ± 0.93
Pine	0.2 M NaOH + heat	120, 1 h	19.83 ± 2.36
Spruce	white rot	6 weeks	0.31 ± 0.58
Spruce	white rot + heat	6 weeks, 1 h	5.45 ± 3.13
Spruce	0.2 M NaOH	120 h	N/A
Spruce	0.2 M NaOH + heat	120 h, 1 h	N/A

Figure 4. Penetration depth of NaOH into pine and spruce wood as a function of time. The insert shows a spruce wood block (as supplied from the luthier – the wedge shape is the starting dimension for the violin top plate).

Data availability statement

All data are available on request.