Summary of significant accounting policies (Schedule of Inventories) (Details) - USD ($)	Mar. 31, 2021	Dec. 31, 2020
Inventories
Raw materials and supplies	$ 833,242	$ 773,021
Work-in-process	109,164	87,159
Finished goods	2,532,050	2,312,148
Total	$ 1,417,440	$ 1,485,986

Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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Aggregated amount of unprocessed materials to be used in manufacturing or production process and supplies that will be consumed. This amount is net of valuation reserves and adjustments.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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