| Immersion time Items | Before modified | 3 h | 6 h | 9 h | 12 h |
| 38 wt%HCl-Rs (Ω) | 4.3 × 1012 | 7.0 × 109 | 1.5 × 1013 | 6.0 × 1013 | 7.5 × 1013 |
| 85 wt%H3PO4-Rs (Ω) | 2.8 × 1013 | 1.0 × 107 | 1.0 × 1013 | 8.0 × 1013 | 1.0 × 1014 |