Note 6 - Investments in Joint Ventures (Tables)

6 Months Ended

Feb. 28, 2015

Equity Method Investments and Joint Ventures [Abstract]

Condensed Balance Sheet [Table Text Block]

	At February 28, 2015
	Total		EXCOR		All Other
Current assets	$	46,802,727	$	19,669,250	$	27,133,477
Total assets		50,375,058		21,662,648		28,712,410
Current liabilities		12,347,251		2,837,566		9,509,685
Noncurrent liabilities		1,080,425		—		1,080,425
Joint ventures’ equity		36,947,382		18,825,082		18,122,300
Northern Technologies International Corporation’s share of joint ventures’ equity		18,377,038		9,412,543		8,964,499
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	$	16,252,890	$	9,381,638	$	6,871,252

	At August 31, 2014
	Total		EXCOR		Tianjin Zerust		All Other
Current assets	$	61,491,957	$	24,361,157	$	9,774,680	$	27,356,120
Total assets		65,466,964		26,652,165		9,793,803		29,020,996
Current liabilities		17,542,634		3,512,143		4,438,380		9,592,111
Noncurrent liabilities		1,929,488		—		868,377		1,061,111
Joint ventures’ equity		45,994,842		23,140,022		4,487,046		18,367,775
Northern Technologies International Corporation’s share of joint ventures’ equity		22,961,989		11,570,013		2,243,524		9,148,452
Northern Technologies International Corporation’s share of joint ventures’ undistributed earnings	$	20,540,523	$	11,539,108	$	2,193,524	$	6,807,891

Condensed Income Statement [Table Text Block]

	Six Months Ended February 28, 2015
	Total		EXCOR		Tianjin Zerust		All Other
Net sales	$	52,178,238	$	18,383,653	$	3,735,457	$	30,059,128
Gross profit		25,540,546		9,766,973		1,783,673		13,989,900
Net income		6,152,182		3,924,547		265,648		1,961,987
Northern Technologies International Corporation’s share of equity in income of joint ventures	$	3,081,331	$	1,962,047	$	132,824	$	986,460

	Six Months Ended February 28, 2014
	Total		EXCOR		Tianjin Zerust		All Other
Net sales	$	58,050,376	$	18,963,579	$	8,257,630	$	30,829,167
Gross profit		27,600,668		10,072,948		3,834,419		13,693,301
Net income		5,479,724		3,763,017		553,963		1,162,744
Northern Technologies International Corporation’s share of equity in income of joint ventures	$	2,823,199	$	1,881,705	$	276,948	$	664,546