Why does oil paint take so long to dry?

Related questions

1. Does heat make oil paint dry faster?
2. How do you soften an oil painting?
3. Are oil paints toxic?
4. Can I paint over an oil painting?
5. Can gesso be used as paint?
6. What does linseed oil do to oil paint?
7. Can you apply gesso over oil paint?
8. Is acrylic paint safer than oil?
9. What should I use to prime a canvas for oil painting?
10. Do you have to let gesso dry before painting?

Tags

1. #water
2. #something
3. #paint
4. #evaporates
5. #process
6. #answer
7. #depending