Note 10 - Activity of Business Segments - Reconciliation of Total Segment Income to Total Consolidated Net Income (Details) - USD ($)		3 Months Ended		9 Months Ended
	Jul. 01, 2017	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consolidated net income	$ 1,103,000	$ 1,539,000	$ 1,103,000	$ 3,007,000	$ 2,457,000
Provision for income taxes	$ 503,000	359,000	503,000	653,000	1,068,000
Operating Segments [Member]
Consolidated net income		2,324,000	2,499,000	6,693,000	6,853,000
Operating Segments [Member] | Building Supply [Member]
Consolidated net income		1,130,000	1,339,000	3,191,000	3,471,000
Operating Segments [Member] | Disposable Protective Apparel [Member]
Consolidated net income		809,000	764,000	1,990,000	1,977,000
Operating Segments [Member] | Infection Control [Member]
Consolidated net income		385,000	396,000	1,512,000	1,405,000
Corporate, Non-Segment [Member]
Consolidated net income		$ 426,000	$ 893,000	$ 3,033,000	$ 3,328,000