Note 4 - Property and Equipment, Net (Details Textual)		3 Months Ended	9 Months Ended
Feb. 28, 2023 USD ($) ft²	May 31, 2023 USD ($)	May 31, 2022 USD ($)	May 31, 2023 USD ($)	May 31, 2022 USD ($)
Payments to Acquire Property, Plant, and Equipment				$ 2,607,988	$ 961,704
Depreciation expense		$ 277,253	$ 291,452	$ 766,091	$ 722,443
Property Immediately Adjacent to NTIC’s Headquarters in Circle Pines, Minnesota [Member]
Area of Real Estate Property \| ft²	26,000
Payments to Acquire Property, Plant, and Equipment	$ 1,200,000

The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482740/230-10-45-28

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482099/360-10-50-1

Name:	us-gaap_Depreciation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration