Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended	12 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2020 USD ($) shares	Jun. 30, 2019 USD ($) shares	Jun. 30, 2018 USD ($) shares
Advertising Expense		$ 3,550	$ 0	$ 2,000
FIFO Inventory Amount	$ 2,408,878	2,408,878	2,308,377
Decreases In Cost Of Goods Sold		0	120,965	242,885
Inventory Valuation Reserves	$ 1,849,134	$ 1,849,134	1,800,935
Entity Number of Employees	218	218
Collective Bargaining Period Expiry Date		May 31, 2021
Health Care Insurance Accrued Liabilities	$ 150,000	$ 150,000	210,000
Research and Development Expense		595,236	459,455	472,077
Share-based Compensation		2,415	$ 3,097	$ 2,830
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	3,000	$ 3,000
Weighted Average Number of Shares Outstanding, Basic and Diluted | shares		4,013,537	4,013,537	4,013,537
Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount		$ 1,000	$ 1,000	$ 1,000
Environmental Remediation Expense	$ 200,000	1,119,155
Payment of environmental liabilities		$ 82,155
Minimum
Property, Plant and Equipment, Useful Life		3 years
Maximum
Property, Plant and Equipment, Useful Life		35 years
Collective Bargaining Agreement [Member]
Entity Number of Employees	139	139