We present experimental results and Monte Carlo studies of the dependence of the transmission efficiency for cylindrical light guides for the FCAL as a function of light guide length and surface treatment. Light guides that are wrapped in aluminized mylar foil are more efficient than those that are unwrapped or have a vapor-deposited aluminum finish. Coupling of the light guides to the lead glass blocks can be achieved using a Sylgard cookie and the application of less than 2 pounds of force. Parallel alignment of the light guide and lead glass surface is critical. The final light guide and optical joint is expected to provide a net transmission efficiency for Cherenkov light that is 2.3 times larger than what can be obtained by coupling the phototube to the block with a small airgap, as used in the RadPhi experiment.
