Grimké Sisters Sarah and Angelina Grimké sat for these portraits around 1840, at ages 48 and 35. Day caps were typical indoor wear for most older women and for Quaker women of all ages. Caps kept hair neat and in place. As important, they signaled modesty, in contrast to fancily coiffed or loose hair, which sent a different signal.
Sarah Grimké: Library of Congress, 3a03340; Angelina Grimké: Library of Congress, 3a03341.