Note 14 - Significant Customers / Concentration (Tables)

12 Months Ended

Dec. 31, 2017

Notes Tables

Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block]

	For the Year Ended December 31
	2017		201 6
United States and Canada	$	1,115,447	$	689,766
Australia		640,322		387,807
South America		89,438		115,675
Asia		1,608,822		1,105,272
Europe		7,889,148		11,607,874
	$	11,343,177	$	13,906,394

Reconciliation of Revenue from Segments to Consolidated [Table Text Block]

	For the Year Ended December 31
	2017		201 6
Ceramic diesel particulate	$	7,230,416	$	5,820,793
Liquid filters and systems		3,987,424		7,731,079
Kiln furniture		125,337		354,522
	$	11,343,177	$	13,906,394