A sticky history of caulk

By RosieHistory · September 2026

Every bead of caulk you've ever laid is the latest entry in a very old argument between people and water. Long before anyone squeezed a tube, sailors, builders, and glaziers were pressing sticky things into cracks and hoping for the best. Some of their tools and words are still with us. So, unfortunately, are some of their materials, but we'll get to that.

A note before we start: history is full of good stories that turn out not to be true. Where the record is fuzzy, we'll say so.

A word that means "to tread"

The English word caulk (also spelled calk) comes from Middle English, by way of Old North French cauquer, "to press down" or "to tread," and ultimately from the Latin calcare, "to tread or press," built on calx, "heel." By the 1400s English was using it for the job of pressing material into the seams of a ship to make them watertight. That's the whole idea of caulking, then and now: you press it in.

The same Latin root gave us inculcate, which originally meant to stamp something in with your heel. We like to think that's what we're doing to you right now, but gently.

Before the word: pitch, bitumen, and reeds

The first great sealant was free for the taking. Natural bitumen, a thick tar that seeps out of the ground in parts of the Middle East, was used in ancient Mesopotamia to waterproof reed boats and baskets and to set bricks. The flood story in the Epic of Gilgamesh describes its hero pouring bitumen and pitch into the making of his boat, and the Book of Genesis instructs Noah to cover the ark "within and without with pitch." Whatever you make of either vessel, the writers clearly knew what a boat needed.

Around the Mediterranean and in northern Europe, pitch and tar made from pine resin did the same work on wooden hulls for thousands of years. If it floated and it was made of wood, somebody had smeared something sticky on it.

The age of wooden ships

Ships built with planks laid edge to edge had long seams that had to be packed tight. That was the caulker's job, and it was a skilled trade. The caulker drove oakum, loose fibers of hemp or jute, often tarred and often picked from old rope, into each seam with a flat-bladed caulking iron and a wooden caulking mallet. The ring of mallet on iron was the soundtrack of a shipyard. Then the seam was sealed over with hot pitch. Sailors called that "paying" the seam, from an Old North French word that goes back to the Latin for covering something with pitch.

Oakum had a grim afterlife on land. In 19th-century Britain, inmates of workhouses and prisons were commonly set to "picking oakum," pulling apart old tarred rope by hand to supply the shipyards with fiber. It was slow, painful work, and it turns up in the literature of the era as a byword for drudgery.

Caulking also sits in the life of one of America's great writers. Before his escape from slavery in 1838, Frederick Douglass learned to caulk ships in the shipyards of Baltimore and was hired out as a caulker, handing his wages over to his enslaver. He wrote about the work, and the violence he faced in the yards, in his autobiographies. It's a reminder that the history of any trade is really the history of the people who did it.

The devil to pay (maybe)

You've probably heard this one. On a wooden ship, the story goes, "the devil" was the name for a particularly awkward seam, usually said to be the one along the keel or right at the waterline, that was miserable to reach and to seal. Hence "the devil to pay, and no pitch hot": a nasty job and nothing to do it with. Some tellings stretch the same seam to explain "between the devil and the deep blue sea."

It's a wonderful story, and it's probably not the origin. Most etymologists are skeptical, because "the devil to pay" shows up in the sense of settling accounts with the Devil himself, as in a bargain come due, well before anyone writes about a seam called the devil. The nautical version looks like a later explanation attached to a phrase sailors already used. We'd love it to be true. The evidence says otherwise. Tell it at parties anyway, with an asterisk.

Windows, putty, and the first caulking compounds

As window glass became common in ordinary houses, so did glazing putty: a dough of linseed oil and whiting (powdered chalk) that holds glass in wooden sashes and slowly hardens as the oil cures. It worked well as long as it was painted, and people who restore old windows still use it today. Some older putties and glazing compounds also contained lead or asbestos, which is one reason old window work deserves care.

Around the turn of the twentieth century, oil-based "caulking compounds" (drying oils mixed with fillers) became the everyday way to seal joints around houses. They were cheap and easy, but they tended to harden, shrink, and crack as they aged. Hand-operated caulking guns were in use by the early twentieth century, and over the following decades the disposable cartridge became the standard way to buy the stuff. The basic shape of the tool you own was set a long time ago.

Chemistry arrives

Polysulfide: the accidental rubber

In the 1920s, a Kansas City chemist named Joseph C. Patrick, reportedly trying to make antifreeze, produced a foul-smelling rubbery material instead. It became Thiokol, one of the first commercial synthetic rubbers in the United States. Liquid polysulfide polymers followed, and sealants made from them became among the first high-performance elastomeric sealants, used for jobs like aircraft fuel tanks and, in the postwar building boom, the joints of glass-and-metal curtain-wall buildings. Polysulfide is still used today, including in the seams of teak boat decks, which brings the story neatly back to ships.

Silicone: from the lab to the bathtub

The English chemist Frederic Kipping did pioneering work on silicon-based compounds at the start of the twentieth century and gave silicones their name. Commercial silicones arrived in the 1940s, with companies including General Electric and Dow Corning among the pioneers. In the decades that followed, one-part room-temperature-vulcanizing (RTV) silicone sealants, which cure by reacting with moisture in the air, made their way from industry to hardware stores. Eventually a tube of bathroom silicone became as ordinary as a roll of paper towels.

Acrylic latex: water cleanup changes everything

The water-based acrylic emulsions that transformed house paint after the Second World War also gave us acrylic latex caulk: low odor, easy to tool, paintable, and cleaned up with water. It took over interior finishing work in the second half of the century, and it's still the most common tube in the aisle.

Polyurethane and the tough stuff

Polyurethane sealants added a tough, abrasion-resistant, paintable option for concrete, masonry, and exterior joints. They're the reason your driveway joints and siding can be sealed with something that actually keeps up with the weather. Read more in our polyurethane guide.

The part of the story we're still cleaning up

Not every advance aged well. In the United States, some caulks used in buildings built or renovated between about 1950 and the late 1970s contained PCBs, added for flexibility and durability. PCB manufacturing was banned in the U.S. in 1979, but some of that caulk is still in place, particularly around windows and masonry in older schools and commercial buildings. Asbestos also turns up in some older caulks, putties, and mastics. If you're removing old caulk from a building of that era, read the safety section of our removal guide first.

Hybrids and the modern aisle

In the late 1970s, the Japanese chemical company Kaneka introduced "MS Polymer," a silyl-modified polymer that cures with moisture like silicone but can be painted like polyurethane, without polyurethane's isocyanates. Those hybrid sealants have become a favorite of pros who want one tube for many materials. Meanwhile, air-quality rules, notably in California, pushed manufacturers toward lower-VOC formulas across the board.

The result is today's caulk aisle: silicones for wet work, latex for paint, polyurethanes for concrete, butyls for flashing, elastomerics for siding, acoustic sealants for quiet rooms, fire-rated sealants for penetrations, and hybrids that try to do it all. A caulk for every crack. The caulkers with their mallets would be amazed, and then, we suspect, a little suspicious of anything that doesn't come out of a hot pot.

The timeline at a glance

Dates are approximate on purpose. Where historians disagree, we've gone with the broad consensus and skipped the tall tales.

History Chemistry