Bonding is a undercoat plaster for low suction background like concrete. Hardwall has high impact resistance and is quicker drying. Browning is a undercoat plaster for moderate backgrounds with adequate mechanical key. A lot of plasterers now seem to use Hardwall. It's better than Browning (tougher) and doesn't need a low suction background like Bonding does. It can be used on brick, Celcon, Thermalite, Plasmor.