The medium of choice for both mounting and long-term storage of slides. Consists of a synthetic resin dissolved in toluene. Low viscosity means easier application, bubble-free preparations. Gives a thinner adhesive layer for better optical quality. A refractive index near that of fixed protein helps keep image free of optical imperfections such as diffraction halos. Suitable for mounting cover slips to slides with thick or thin specimens. Won't shift the colors of biological dyes. Use it with artificial or natural light. Won't lose its cohesiveness, adhesive quality, or color with age. Preserves most biological dyes with little or no fading when slides are stored in darkness. Contains an antioxidant to prevent formation of annular rings. High softening point 155C (311F) makes it exceptionally suitable for microprojection.