Note 2 - Inventory - Summary of Inventory (Details) - USD ($)	Jun. 30, 2019	Dec. 31, 2018
Furnace parts and supplies	$ 730,370	$ 596,806
Raw materials	1,756,414	1,659,826
Work in process	1,501,307	1,691,175
Finished goods and filtration systems	1,527,554	1,596,042
Reserve for obsolescence	(801,990)	(1,111,794)
Net Inventory	$ 4,713,656	$ 4,432,055

Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer.

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