Table 5.
Colour values measured on sound St. Margarethen Limestone (SM) and Schlaitdorf Sandstone (S) before and after treatment at different intervals: six weeks (6 w) and twelve months (12 m).
| Stone | Treatments | ΔL* (6 w) |
ΔL* (12 m) |
Δa* (6 w) |
Δa* (12 m) |
Δb* (6 w) |
Δb* (12 m) |
ΔE* (6 w) |
ΔE* (12 m) |
|---|---|---|---|---|---|---|---|---|---|
| SM | KSE 300 | 4.51 | 6.62 | 0.87 | 0.45 | 5.30 | 4.53 | 7.01 | 8.03 |
| NC-25C | 0.87 | 2.71 | 1.29 | 0.92 | 5.15 | 3.98 | 5.38 | 4.90 | |
| NC-27CP | −1.41 | 0.44 | 2.10 | 1.51 | 7.31 | 6.15 | 7.74 | 6.35 | |
| S | KSE 300 | −5.49 | 2.46 | 1.10 | 0.81 | 5.80 | 3.84 | 8.06 | 4.63 |
| NC-25C | 0.30 | 2.77 | 0.76 | 1.39 | 2.86 | 5.04 | 2.97 | 5.92 | |
| NC-27CP | −2.57 | 1.63 | 0.61 | 0.75 | 0.76 | 0.66 | 2.75 | 1.91 |
L* the lightness coordinate ranging from 0 (black) to 100 (white), with positive values meaning darkening; a* the red/green coordinate, with +a* indicating redness and –a* indicating greenness; and b* the yellow/blue coordinate, with +b* indicating yellowness and –b* indicating blueness.