Characteristics | Specification/defects | Tolerances |
Appearance characteristics | Cracks - Deformation - Blistering - Tearing - Flatness Edge straightness - Surface condition | Visual criteria to be checked and flexion not exceeding 5 mm |
Physical characteristics | Bursting | No white spot |
| Shrinkage | <8% |
Water absorption | <15% | |
Loss on ignition | <15% |