Sunflower oil is used as a cooking oil and to add flavour to dressings, sauces and other dishes. All sunflowers seeds contain oil, but sunflower varieties labelled as oilseed have a higher concentration of oil. Oil-seed is often sold as birdseed. When pressing the seeds at home, it is rarely possible to extract all the oil from the seeds. Heating helps the seeds release more oil and makes it easier to extract it without using specialised equipment.
Shell the sunflower seeds soon after harvest. Place the seeds into pot once the shells are removed.
Heat the seeds over low heat, stirring constantly. Heat the seeds until they are hot to the touch but remove them before they begin to brown and turn golden.
Place the warm seeds into a mortar and crush them coarsely with a pestle. Alternate, run the seeds through an apple mill or crush them in a food processor.
Line a mesh sieve with cheesecloth. Fill the sieve with crushed seeds and place it over a bowl.
Place a second sheet of cheesecloth over the seeds. Place weights, such as clean river stones or pie weights, on top the cheesecloth. The weights press the oil out and into the bowl, a process that may take three or more hours. Apply pressure on top the weights to help speed the process.
Cover the bowl with cheesecloth to keep dust out of the oil. Leave the bowl to stand at room temperature for three days.
Skim the surface of the oil with a spoon, removing the cloudy oil on top. Pour the oil through a sheet of cheesecloth to remove any remaining seed pieces.
Store sunflower oil in tightly sealed containers for 6 to 12 months. Keep the oil in a dark, cool area such as in a basement or pantry. Commercial seed oil presses are available that speed up the oil extraction process.