Plastic deformation may be introduced in LiF single crystals by abrading, quenching, or bending. For x‐ray wavelengths of about 1.5 AU(CuK&agr;) the diffracting power is increased about 4 times by any of the three methods. For shorter wavelengths of about 0.7 au(MoK&agr;) the increase in diffracting power is about 4, 7, and 10 times for abrading, quenching, and bending, respectively. The bent crystals are more effective at shorter wavelengths because the plastic deformation is more uniform throughout the crystal while in the abraded crystal, all the deformation is concentrated in a layer extending only 0.002 inch below the surface. The extent and concentration of plastic deformation is shown by selective etching of dislocation sites.