a typical embodiment of the invention a container is provided with a congruent flexible core which is inserted into the container to force the material into the space lying between the container and the core expansion of the material on freezing acts to deform the flexible core rather than to break the container the material thus frozen into a shell like conformation within the container is then subjected to a lyophilization process after removal of the flexible core application_number US 17255688 A description referring now to the drawings and particularly to fig1 and 2 a lyophilization flask 10 is seen to have a cylindrical portion 12 closed at one end by rounded bottom 14 the open end of flask 10 is bordered by bead 16 the flask 10 is preferably formed of a borosilicate glass such as is commonly employed for the manufacture of glass flasks the flask 10 can be formed of materials other than borosilicate or similar glasses it only being necessary that the chosen material have the capability of withstanding the low temperatures encountered in the freezing process which will be practiced to freeze within the flask a material which is to be lyophilized while contained within the flask the freezing process employed can vary from those temperatures encountered in a typical domestic freezer to dry ice temperatures such as would be encountered in a dry ice acetone bath the flask 10 can be provided with indicia 18 to allow measurement of the quantity of liquid material which is poured into the flask.