Note 9 - Significant Customers / Concentration / Disaggregated Revenue - Sales by Product Line (Details) - USD ($)	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Net Sales	$ 7,421,198	$ 2,391,382
Ceramic Diesel Particulate [Member]
Net Sales	2,243,268	1,770,493
Liquid Filters [Member]
Net Sales	5,040,333	463,277
Development Projects [Member]
Net Sales	$ 137,597	$ 157,612

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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration