There is a common misconception that pores open and close, but they actually don’t expand or contract. That said, there are some things you can do to help unclog debris in the pores, which will make them appear smaller. In addition to regularly using a mask meant to treat large pores, add a chemical exfoliant to your skincare routine. Salicylic acid (a beta hydroxy acid) is the best ingredient for large pores, because it is oil-soluble and works deep in the pores, dissolving excess sebum and debris (which make the pores appear larger).