Table 1. pH Values and Percentage of Chromophore Reduction, CR(%), before and after the Cleaning Processes.

	Breviarium		Office
	pH	CR (%)	pH	CR (%)
before cleaning	6.7 ± 0.2		4.9 ± 0.2
0.10% microgel	7.6 ± 0.2	83	5.5 ± 0.2	19
0.75% microgel	8.1 ± 0.3	76	5.9 ± 0.2	15
Gellan gel	7.6 ± 0.2	49	5.5 ± 0.3	22
water bath	7.8 ± 0.2	80	5.3 ± 0.2	41