For the bentonite, which is used as a binder, the distinguishing parameters are swelling capacity, gelling index, gel time, Base Exchange capacity, liquid limit and green compressive strength. It has been observed that bentonite used for medium-grade casting and for palletizing of iron ore is required to have similar properties, similarly the bentonite used in foundry industry and in civil construction works (water well, drilling and dam, canals and reservoirs, etc.) should have similar properties. The bentonite required for high-grade casting must be better in quality than the bentonite used in other industries as a binder. The distinguishing particular of specifications of bentonite for use as a binder for different purpose are given below:
| Particulars | Medium-grade Casting & palletizing |
Foundry industry water well drilling & dam canals & reservoirs |
High-grade casting |
| Swelling capacity (2gm. In 100ml D.W) |
12 - 14 | 16 - 20 | 25 - 45 |
| Gelling index (MgO test) | 20 - 25 | 35 - 45 | 65 - 72 |
| Gel time (minutes) | 7 - 10 | 5 - 7 | Instant |
| Base exchange capacity Mgg./100 g | 60 - 65 | 60 - 70 | 75 - 100 |
| Liquid limit (%) | 250 - 275 | 285 - 315 | 335 - 600 |
| Green compressive strength PSI (Bent/H2O: 7/3) | 7 - 8 | 8 - 9.5 | 9.5 - 12 |
| Type of bentonite | Sodium bentonite | ||