If you have some liquid from roasting, stew or soup etc and you want to separate the fat, I believe the normal methods is to get a spoon and remove it from the top or let it come to room temperature, solidify and then remove it.
If it solidifies and you remove it, isn't it only the saturated fat you are removing while the unsaturated fats stay behind? How do you remove unsaturated fats also?
Saturated fats (eg the white part of a steak or chop) are generally solid at room temperature while unsaturated (eg olive oil) are not. Generally the advice for getting fats out of soups and stews is to chill it so it all solidifies. Since it floats whether it is solid or not, there are also techniques like skimming, absorbing with a paper towel or bread, etc. (See How can I remove excess fat from stews or soups without refrigerating? for examples.)
The temperature at which something solidifies is a poor way to test whether a fat is saturated or unsaturated, and it's not an important distinction really. If it's important to you to get all the fat from something, then chilling and waiting is probably the most effective way. If you don't have time for that then you either eat a little fat (which for most people is fine) or you make a different dish.
