It took more than a week for the big bronze bell to cool. Over that time, a glowing crucible full of molten alloy was transformed into a 7,595-pound behemoth nearly six feet in diameter that next year will sing out across Arlington.

The big Netherlands Carillon is getting bigger.

“Of course, theoretically, you could speed up the cooling process, but that would be disastrous for the sound,” said Joost Eijsbouts, the chief executive of Dutch bell foundry Royal Eijsbouts.

No, slow and steady is the way to go. Allow the bell to cool at its own pace, and it will reward you with a tone that’s clear and true.

The Netherlands Carillon was dedicated near Arlington National Cemetery in 1960, a gift from the Dutch people as a thank-you for the assistance the United States provided during and after World War II.

“The carillon for us is a symbol of international cooperation,” Dutch Ambassador André Haspels said during a Zoom chat.

Last month, to mark the 75th anniversary of the end of the war, three new bells were cast at the Royal Eijsbouts foundry in the Netherlands, which has been in Joost Eijsbouts’s family since 1872.

A bell has a utilitarian function — to make noise. But the best bells — like these three — have a symbolic function, too.

“We decided to name them after three persons who obviously have played a very important role in the last 75 years,” Haspels said.

The largest bell is named in honor of Gen. George C. Marshall, architect of the Marshall Plan, which helped rebuild Europe. A 37 ½-pound bell is named in honor of the Rev. Martin Luther King Jr. to celebrate the work King did for human rights and minority rights. A 26 ½-pound bell is named after Eleanor Roosevelt, whom the Dutch love not only for her work on women’s rights but also because of her Dutch ancestry.

The three additional bells will join the 50 that were already part of the Netherlands Carillon. Last October, those bells were carefully removed, packed up and sent home to be refurbished. While they’re out, the carillon’s 127-foot-tall structure is being restored. (I hope we take better care of it this time, since it seems that every other decade we act surprised that it’s gotten rusty and derelict and in need of emergency support.)

The addition of the three bells will make the instrument a grand carillon, which is a big deal in the carillon world.

A carillon is played with a keyboard and pedals, unlike the bells at the Old Post Office, which are played with ropes. It’s a typical instrument of the Low Countries, introduced centuries ago as a way to get the attention of far-flung people so they’d know what time it was.

Now its musical qualities are celebrated. Go to an organ concert and if you don’t like the repertoire, you can leave. That’s hard to do with a carillon, where the music pours down from a great height to everyone within earshot.

“That also gives an obligation the musician should be aware of,” Eijsbouts said. “You should play music that is fine for everyone.”

It took four weeks to construct the mold for the Marshall bell. The bronze was poured on April 9 — with appropriate social distancing, the embassy noted. After 10 days, the remains of the mold — sand, largely — were removed. Then the bell was sandblasted clean and the canals that allowed the alloy to flow into the mold were ground off.

The three bells were placed on a lathe and the metal surface shaved to achieve the correct tone. The 50 previous bells also were freshened up. The result is an extremely accurate musical note.

“After two days, a piano might need another tuning service, whereas, once tuned, the bells stay in tune,” Eijsbouts said.

When the bells are finished, they’ll be loaded into a pair of 40-foot sea containers and shipped back to the United States. The rededication should take place in the first half of 2021.

Hundreds of World War II veterans attended a 50th anniversary celebration at the Netherlands Carillon in 1995. That probably won’t happen next year — the youngest vets are in their mid-90s — which adds even more urgency to the story the bell tower tells. The new generation does not automatically learn the stories of the old.

Said Haspels: “From history we can learn for the future.”

That has a nice ring to it.

Correction: An earlier version of this story indicated that Washington National Cathedral did not have a carillon. The cathedral has both a carillon and peal bells..

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/john-kelly.