Note 11 - Segment Reporting - Segment Information (Details) - USD ($)		3 Months Ended		9 Months Ended
		Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Jun. 30, 2019
Assets		$ 46,166,104		$ 46,166,104		$ 46,723,052	$ 49,534,000
Revenue		3,993,204	$ 5,704,882	13,748,448	$ 14,100,261
Operating loss		(1,392,653)	(248,571)	(2,416,745)	(4,357,007)
Pretax loss		(1,291,641)	(139,009)	(2,297,186)	(4,399,382)
Intersegment Eliminations [Member]
Assets	[1]						(9,000)
Revenue	[1]	(131,000)	(175,000)	(390,000)	(641,000)
Operating loss	[1]	(738,000)	(597,000)	(2,229,000)	(2,501,000)
Pretax loss	[1]	(738,000)	(597,000)	(2,229,000)	(2,501,000)
CVD [Member] | Operating Segments [Member]
Assets		34,888,000		34,888,000			36,389,000
Revenue		2,308,000	4,376,000	8,686,000	9,588,000
Operating loss		(283,000)	231,000	10,000	(2,328,000)
Pretax loss		(267,000)	226,000	10,000	(2,297,000)
SDC [Member] | Operating Segments [Member]
Assets		6,202,000		6,202,000			6,689,000
Revenue		826,000	1,100,000	3,661,000	3,778,000
Operating loss		(111,000)	254,000	556,000	936,000
Pretax loss		(111,000)	260,000	564,000	951,000
Materials [Member] | Operating Segments [Member]
Assets		5,076,000		5,076,000			$ 6,465,000
Revenue		990,000	404,000	1,791,000	1,375,000
Operating loss		(261,000)	(137,000)	(754,000)	(464,000)
Pretax loss		$ (176,000)	$ (28,000)	$ (642,000)	$ (552,000)

[1] All elimination entries represent intersegment revenues eliminated in consolidation for external financial reporting.