A method for providing a smoothly mixed slurry to a web is provided which includes inserting calcined gypsum and water into a mixer (12), agitating the contents of the mixer (12) to form an aqueous dispersion of the calcined gysum, and passing the agitated contents from an outlet (20) of the mixer (12) into a slurry dispensing apparatus (22) including a flexible, resilient conduit (24). Additionally, the method includes the step of creating a back-pressure on the mixture in the slurry dispensing apparatus by constricting the conduit (24). The constricting of the conduit (24) is effected by a constrictor valve (28) located on the conduit (24).