Her approach to portraiture favoured a direct, observational style that avoided the sentimental trends of the Victorian era. Putnam used a muted palette and clear lighting to define the features of her subjects. This method allowed the personality of the subject to remain the primary interest of the composition. By concentrating on anatomical accuracy and natural poses, she created likenesses that felt grounded in reality. Her sketches often depict her subjects in moments of quiet reflection rather than formal arrangements.

Modern collectors value Putnam for her visual documentation of New England intellectuals. Her portraits of subjects like the poet Amy Lowell provide a connection to the academic progress of the late nineteenth century. These works function as historical records and studies of character. The understated nature of her technique makes these prints suitable for contemporary interiors that require a sense of history without excessive ornamentation.