Answer: Pore size is genetic. The size of your pores can't actually change, no matter what you do, so you can't physically shrink them or make them disappear. The whole use warm water to open your pores and cold water to close your pores is a complete myth.Pores on your skin cannot and do not open and close. However, there are things you can to do make large pores appear smaller: Exfoliate to keep pores clean.Dead skin cells and clogged sebum can build up in your skin and make pores larger than they actually are.ores on your skin cannot and do not open and close. However, there are things you can to do make large pores appear smaller: Exfoliate to keep pores clean. Dead skin cells and clogged sebum can build up in your skin and make pores larger than they actually are.