Northern Technologies International, the Circle Pines-based maker of corrosion inhibitor products and services, said its latest quarterly revenue dropped significantly as key markets for its products were largely shut down due to coronavirus restrictions.

"Although our operations were deemed essential and remained open throughout, the COVID-19 pandemic had an unprecedented impact on our worldwide business during the third quarter, as the majority of our global customers operated at significantly lower capacities or were locked down altogether," G. Patrick Lynch, the company's chief executive, said in a statement.

The company lost $965,000, or 11 cents a share, during the three months ended May 31, the third quarter of its fiscal year. It earned $1.5 million, or 16 cents a share, in the same period a year ago.

Revenue fell 35% to $9.7 million.

The company's Zerust rust and corrosion inhibiting products are used in the automotive, electronics, mechanical and other markets. The firm has been expanding in the oil and gas sector and also offers technical consulting on corrosion resistance.

Sales of Zerust products to industrial customers, its biggest market, amounted to $6.3 million, down 24% from the third quarter last year. Sales to the oil and gas sector were $424,000, a 52% decline.

Lynch said that as global economies have begun to reopen, Northern Technologies has seen business begin to improve. "We currently believe our fourth-quarter financial results will regain ground from third-quarter levels, but sales and earnings will likely be lower than they were during the same period in 2019," Lynch said.

Shares of Northern Technologies were trading at $7.58 per share, up 6.7% Wednesday.