American Companies are having difficulties selling N95 masks despite shortages.

A year into the pandemic, the disposable, virus-filtering N95 mask remains a coveted piece of protective gear. Continuing shortages have forced doctors and nurses to reuse their N95s, and ordinary Americans have scoured the internet — mostly in vain — to get them.

But Luis Arguello Jr. has plenty of N95s for sale — 30 million of them, in fact, which his family-run business, DemeTech, manufactured in its factories in Miami. He simply can’t seem to find buyers.

After the pandemic exposed a huge need for protective equipment, and China closed its inventory to the world, DemeTech, a medical suture maker, dived into the mask business. The company invested tens of millions of dollars in new machinery and then navigated a nine-month federal approval process that allows the masks to be marketed.

But demand is so slack that Mr. Arguello is preparing to lay off some of the 1,300 workers he had hired to ramp up production. ...

In one of the more confounding disconnects between the laws of supply and demand, many of the nearly two dozen small American companies that recently jumped into the business of making N95s are facing the abyss — unable to crack the market, despite vows from both former President Donald Trump and President Biden to “Buy American” and buoy domestic production of essential medical gear.