A hollow edge blade is a knife blade with a series of evenly spaced vertical indentations close to the cutting edge. These indentations confer several advantages to this type of blade, making the blade very popular in busy kitchens. Many knives designed for sushi, such as santoku knives, are hollow edge blades. Any reputable kitchen supply store will carry an assortment of such blades to choose from, and they can also be ordered directly from knife manufacturers.
This type of knife blade should not be confused with a hollow ground blade. A hollow ground blade is ground, or prepared for finishing, in a very distinct way. A hollow edge blade may be ground in several different ways, but in all cases indentations are ground out along the length of the knife. These indentations are typically polished so that they are smooth, ensuring that food particles do not stick to rough spots.
Because the grinding removes a chunk of the blade, a hollow edge blade tends to be thinner, generally, than one might expect. These indentations also reduce friction on the blade, which can be extremely useful for cooks who work quickly in the kitchen. In addition, they prevent particles from sticking to the edge of the knife, potentially disrupting clean, even cuts. This style of blade can also be amazingly strong, making it suitable for a wide range of uses in the kitchen.
When a hollow edge blade is made from high quality materials, it will be a solid, sturdy knife which can yield years of use when well cared for. Make sure to never put your knives in the dishwasher, and always wipe them dry after washing to ensure that the blade stays in good shape. In addition, you should use knife guards to protect your knife blades, as well as the fingers of unsuspecting victims. Periodically oil and sharpen your knives to ensure that they stay in good cutting shape.
You may also see a hollow edge blade marketed as a Granton blade. In all cases, try to physically handle a knife, if possible, before purchasing it. If the knife feels suspiciously light, don't buy it, as it may be made from cheap or sub-par materials. Make sure that it feels right in your hand, with the weight balancing appropriately. If the knife feels uncomfortable, it will not perform well in the kitchen.