Note 8 - Significant Customers / Concentration / Disaggregated Revenue - Sales by Product Line (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net Sales	$ 9,672,716	$ 3,347,204	$ 26,391,100	$ 9,336,614
Ceramic Diesel Particulate [Member]
Net Sales	1,330,337	1,841,136	4,320,839	5,085,203
Liquid Filters [Member]
Net Sales	7,920,745	1,426,107	21,414,214	3,878,355
Development Projects [Member]
Net Sales	137,148	79,961	371,561	373,056
Plastic Products [Member]
Net Sales	$ 284,486		$ 284,486

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration