A joint compound system is provided including a main container of base joint compound; and an additive container isolated from the base joint compound and housing at least one and preferably multiple additive packages constructed and arranged so that the additive packages are protected from exposure to moisture prior to their ultimate mixing with the base joint compound.

The invention relates to an improved capsule for substances to be mixed at the time of use. The capsule object of the present invention is applied to close the mouth (1a) of a container (1) containing a solvent (10), and comprises a first part (2), of the known type, intended to be connected to the mouth of the container, and a second part (3), connected to the first part, by a wall (4) which firmly closes the bottom (3a) of the second part (3) and the mouth of the container intended to contain the active substance; the second part has an open upper mouth (3b), which is closed by hermetically removable sealing means when the second part contains the active substance.

A bottle cap is disclosed, which includes a top portion, comprising a hingeable lid, a middle portion, comprising a reservoir for retaining a material, and a bottom portion, which is surrounded by a threading that further comprises a means for attaching to a bottle. The top portion of the bottle cap further comprises a depressible button for exerting pressure in said reservoir, wherein said reservoir further contains a means for releasing said material into said bottle upon the exertion of pressure from said depressible button.