Yes, in some cases, you can do that. Technically speaking, they are designed to work alongside the foundations, powders and concealers. However, you can also wear it alone on a no-makeup day to invisibly perfect your skin. In such a case, a fine quality transparent primer should be your pick. You can take a pea-size amount of prime and apply it to your skin after moisturizer to create a smooth layer. It will cover up all the small pores and leave your skin smooth and oil-free for the day.