Provided are methods and devices for dissolving solid protein compositions, such as solid compositions comprising fibrinogen, in an aqueous solvent. The methods comprise use of a closed container containing a volume of solid fibrinogen composition and a head space wherein the pressure within the headspace is sub-atmospheric. Aqueous solvent is introduced into the container while maintain the sub-atmospheric pressure, and subsequent to addition of the solvent, the size of the headspace is decreased to bring the pressure to atmospheric pressure. The devices are suitable for use in the disclosed method.
