MIAMI — From the outside, Midge Jolly's newest salt house looks like an igloo that went long instead of domed. Inside, though, a block of ice wouldn't stand a chance.

MIAMI — From the outside, Midge Jolly's newest salt house looks like an igloo that went long instead of domed. Inside, though, a block of ice wouldn't stand a chance.

"Actually some friends have asked us if we'll lend it out as a sauna," Jolly says. "It can get to 149 degrees in there in the middle of the day." Perfect for producing buckets of sweat and, in about a month's time, 40 quarts of sea salt.

Jolly and her husband, Tom Weyant, are the founders of Florida Keys Sea Salt. It's selling in several markets in the Keys and has been purchased wholesale (though not yet offered retail) by The Meadow (www.atthemeadow.com), an online gourmet store that sells nearly 100 salts from around the world.

Jolly and Weyant have four salt houses on their property on Sugarloaf Key, the newest 32 feet long, 12 feet wide and 6 feet tall. White plastic sheeting arches over the top, and each end is covered in small-gauge mesh to keep out the bugs ("biologicals" Jolly calls them) and to facilitate evaporation.

Two long, shallow troughs, called pans, run the length of the structure, each of which holds 240 gallons of seawater — about three bathtubs' worth — from nearby Bow Channel.

After 26 days of evaporation, there was the first hint of salt — fine, grayish crystals. In another 10 days or so, when the water has almost completely evaporated, Jolly will scrape up snow-white crystals with her favorite low-tech tool.

"I will bring out a squeegee," she says, "I spent lots of time figuring that out. I used to use spatulas."

She and her husband still are figuring out a lot of things, Jolly says. "We've been at it now in prototype and testing for a long time. But all of a sudden, the thing's in production, which we weren't before, so it seems to outsiders we're knowledgeable"

An early lesson: You can't make sea salt in a lobster pot.

"That virgin batch was ugly, and it really didn't taste good. I had seen an interview with a Scottish chef. Being of Scottish descent myself, I was especially interested. I thought, 'If he can do that, I can do that.'

"We went and got three gallons of water and put it on the stove and cooked and cooked and cooked and — oh my gosh we cooked forever.

"It got down to this gray, sludgy stuff that was just muddy and yucky. I think I took a bath in it," she says with a laugh. "I assure you, we did not eat it."

But they read volumes, they consulted a University of Florida expert, they got help building the salt houses and, suddenly, they're salt farmers.

Jolly sees their endeavor as a link between the Keys' past and future. In the early 1800s, salt-making was a major, and lucrative, industry in the Lower Keys. Natural salt pans lined the eastern edge of Key West, and Bahamian laborers, who had the expertise, made industrialists wealthy.

Everything old is new again, and a blizzard of artisan salts — brick red from Hawaii, dove gray from Brittany, baby-girl pink from Australia — attests to the booming popularity of the ancient craft.

When Jolly and Weyant started out, however, survival was uppermost in their minds. She had been a midwife, but the number of home births in their community declined, and she joined her husband's landscaping business.

"I became a master gardener and connected with native plants. That's really my heart," she says.

In 2005, however, the business, literally, was sunk.

"When Hurricane Wilma came and brought, we think, 13 feet of water under our house, she also brought lots of salt with her and turned our landscaping business upside down," Jolly says. (Fortunately, the house rests on 14-foot stilts.)

In 2006, they founded their new business, and salt became their salvation.