Note 2 - Inventory - Summary of Inventory (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Furnace parts and supplies	$ 621,991	$ 596,806
Raw materials	2,125,921	1,659,826
Work in process	1,624,499	1,691,175
Finished goods and filtration systems	1,492,135	1,596,042
Reserve for excess and obsolescence	(665,308)	(1,111,794)
Net Inventory	$ 5,199,238	$ 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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