Smartphone technology has the potential to make heritage science accessible to museums, individual collectors, and educators. Infrared reflectography (IRR) is a nondestructive analysis method used by museums to gain information about the provenance, history, and aging of artworks. This paper introduces a highly accessible, inexpensive apparatus for near-infrared (NIR) imaging of paintings: a long-pass filter with a 750 nm cut-on wavelength mounted on a Samsung HTC smartphone back-facing camera. This method proved effective in improving visibility of underdrawings, as well as in the detection of compositional changes by the artist, retouchings, and original-composition elements obscured by damage or aging. Egg-tempera test panels, historic oil paintings, and wall murals were all imaged with the NIR-smartphone apparatus. The research presented in this paper demonstrates the potential of adapted consumer technology for interdisciplinary scientific investigation in museums and at heritage sites, which has the potential to raise public understanding of heritage science. This simple and affordable approach is a promising tool for teaching the importance of and principles behind the scientific investigation of artworks.