Inventories (Details) - USD ($)	Jun. 30, 2015	Dec. 31, 2014
Inventories
Raw materials	$ 1,854,302	$ 2,020,151
Work-in-progress	421,764	407,964
Finished goods	1,399,940	1,517,151
Reduction to LIFO cost	(1,312,113)	(1,314,616)
Total inventory	$ 2,363,893	$ 2,630,650