Table 4 Overall colour variation (ΔE), changes in colour coordinates (Δa and Δb) and brightness (ΔL) for PUV1 (grain side) and PUV2 (corium side) parchment samples exposed to artificial ageing for a maximum of 748 h with respect to their unaged condition
Sample | Ageing time (h) | ΔL | Δa | Δb | ΔE |
|---|---|---|---|---|---|
PUV1 (grain side) | 12 | − 0.28 | 0.48 | 2.48 | 2.54 |
83 | 0.08 | 0.23 | 0.93 | 0.97 | |
248 | 0.06 | 0.18 | 0.75 | 0.78 | |
392 | − 0.92 | 0.30 | 1.33 | 1.64 | |
748 | − 1.84 | 0.66 | 2.80 | 3.41 | |
PUV2 (corium side) | 12 | − 2.07 | − 0.27 | 0.98 | 2.30 |
83 | − 1.47 | − 0.26 | 0.20 | 1.51 | |
248 | − 1.58 | − 0.35 | 1.01 | 1.91 | |
392 | − 1.88 | − 0.29 | 1.22 | 2.26 | |
748 | − 0.35 | − 0.26 | 2.71 | 2.74 |