Sunflower seeds are available with or without shells, roasted or raw, salted or unsalted, and as human, livestock or bird food. When snacking on a sunflower seed with the shell, the shell can be cracked by the teeth and then separated from the seed using the tongue or fingers. Birds use their hard beaks to break open the shells. Commercially hulled sunflower seeds have their shells removed by mechanical devises. The hulled seeds can be eaten alone, used as a garnish, added to baked goods or made into sunflower butter or oil.
Mechanical seed dehullers used for separating the sunflower seed from its shell are available from various manufacturers. The machines may vary in design and are typically a conveyor belt process, where the seeds automatically move from one stage of the hulling to the next. The first step usually involves pre-cleaning, where impurities, such as dirt, dust and rocks are filtered from the seeds. The shells are then broken, which might be done by forcing the seeds against blades. After the seeds are broken the motion of the machine (depending on the machine style) helps to separate the seed from the shell. Air is often used to separate the seed from the broken shell. The air blows on the broken shells, forcing the lighter-weight shells away from the heavier kernels.
While the mechanics of sunflower seed dehulling machines varies, the seeds may go through the following steps during the procedure: feeding the seeds into the machine, cleaning, pneumatic elevating, hulling, separating seeds from shells and kernels, elevating, sorting pin-shaped shells and seeds, sorting seeds and kernels. During the elevation process the seeds are typically moved up automatically to a higher elevation in the machine.
For the home gardener, a sunflower dehulling machine would not be a practical option. According to an article by Organic Gardening, some home gardeners have been successful hulling sunflower seeds by using a grain mill to break open the seeds and separating the broken shells from the kernels by blowing with air from a vacuum. Willowing machines are also used. Sunflower seeds with broken shells are added to the machine which uses a controlled air current to separate the kernels and shells.