Idont know if its nessary to freeze because there is no sugar in coffee, i dont when i make it. And it works fine. My coffee is probably room temp or so cause i make that first then get all my soap stuff out. One tip... Mix coffee and lye outside. Man does it stink. And it will continue to stink through mixing and molding. After a good cure i just have a faint cooffee smell fromthe grounds i add at trace. Good luck!