From Salem Wiki
A press is used to get oil from certain seeds. You can press cotton, corn or pumpkin seeds. The press itself has 25 slots for seeds and can hold up to 25L of oil.
- Pressing only Seeds of Corn will yield Corn Oil at a rate of 5L per 100 seeds.
- Pressing only Seeds of Cotton will yield Cottonseed Oil 10L per 100 seeds.
- Pressing only Seeds of Pumpkin will yield Pumpkinseed Oil at a rate of 7.5L per 100 seeds.
Mixing any of the seed oils will turn the oil into Vegetable Oil.