Method of making a light-sealing cap with feature for addition of materials

A method of forming a light-lock cap having a shell and means to seal said shell to a container, comprising:

• providing a fluid-handling insert comprising means to allow passage of liquids through said cap into the container covered by said cap;
• said insert comprising means for liquid passage including a labyrinth passage for liquids with an upward facing inlet and downward facing outlet, said passage for liquids contained in said fluid-handling insert, the inlet for said labyrinth passage for liquids being on an upper surface of said cap and the outlet for said labyrinth passage for liquids being on a lower surface of said cap,
• said insert further comprising means to allow gases to exit said container covered by said cap including a labyrinth passage for gases with a side facing inlet and side facing outlet, said passage contained in said fluid-handling insert, said labyrinth passage for gases having a side facing orifice on the interior of said cap and a side facing orifice on the exterior of said cap,
• said fluid-handling insert further comprising grooves on an outside of said insert,
• placing said insert into a mold cavity,
• and molding the cap around said insert with the cap joining the insert at said grooves;
• wherein said cap and said insert are formed of the same polymer.