Well‐defined beams of thermal and long‐wavelength neutrons are often difficult to obtain because of reflection from collimator surfaces. Reflection is minimized if the product of the number of scatter centers per cm3and their net coherent scattering amplitude is as small a negative number as possible. This amplitude balancing can be achieved to almost any degree by the proper selection of organic compounds. When used as surface coatings, these compounds possess distinct advantages over other materials. Tetradecanoic acid (C14H28O2) has shown extremely low reflectivity and excellent properties as a surface coating.