Note 10 - Activity of Business Segments - Reconciliation of Total Segment Income to Total Consolidated Net Income (Details) - USD ($)	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018
Consolidated net income	$ 437,000	$ 1,010,000	$ 1,218,000	$ 1,539,000	$ 959,000	$ 508,000	$ 2,665,000	$ 3,007,000
Provision for income taxes	110,000			359,000			592,000	653,000
Operating Segments [Member]
Consolidated net income	1,849,000			2,324,000			5,959,000	6,693,000
Operating Segments [Member] | Building Supply [Member]
Consolidated net income	1,010,000			1,130,000			2,819,000	3,191,000
Operating Segments [Member] | Disposable Protective Apparel [Member]
Consolidated net income	839,000			1,194,000			3,140,000	3,502,000
Corporate, Non-Segment [Member]
Consolidated net income	$ 1,302,000			$ 426,000			$ 2,702,000	$ 3,033,000