Salting before pressing is one strategy to put the brakes on the starter bacteria to control acidification. For example, with a cheddar, the point is to get the acid levels to where you want them, then salt to slow down acid production. Colby uses a different strategy of "washing the curds" by removing whey (and a large portion of the lactose) and replacing with water. This limits the food for the bacteria and keeps the cheese from becoming too acidic. After pressing, Colby is brined for flavoring and to partially dehydrate the surface to initiate rind production.