Income Taxes - Deferred tax assets (Details) - USD ($)	Dec. 31, 2020	Dec. 31, 2019
Deferred tax assets
Net operating loss carryforwards	$ 535,000	$ 4,928,000
Interest limitation carryforwards	1,033,000	686,000
Accrued liabilities	391,000	477,000
Accounts receivable	40,000	108,000
Inventory	322,000	587,000
Property, plant, and equipment	(5,509,000)	(5,580,000)
Post retirement benefits	2,068,000	2,090,000
Goodwill and finite-lived assets, net	2,210,000	1,973,000
Other, net	156,000	24,000
Total Deferred Tax Assets	1,246,000	5,293,000
Valuation allowance for deferred tax assets	(1,193,000)	(3,267,000)
Total deferred tax asset, net	$ 53,000	$ 2,026,000

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Amount, before allocation of valuation allowance, of deferred tax asset attributable to deductible interest carryforward.

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Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences and carryforwards.

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