Coming to America: How Cathedral Stone Brought Jahn Mortars to the US Restoration Market
My introduction to Jahn Mortars came as a casual reference to “a scientist in Holland, who was developing a new masonry patching mortar.” This was 1982. I had been patching stone since I was fifteen, and I knew that there was something wrong with our materials. So I was curious and wanted to know more about this scientist in Holland—his name was Heinz Jahn.
I wanted to try this new patching mortar myself. So I wrote a letter to Heinz Jahn, sealed the envelope, and shipped it off via DHL to Holland—not knowing then that the letter would change not only my life, but also the way historic and significant buildings are restored and repaired around the world.
It took a while, but the samples of Jahn Mortar finally arrived at my stone plant. I’d used a lot of different repair materials, but I’d never experienced anything anywhere near as good as Jahn Mortar. It went on so easily, and it stuck to stone like nothing else. A month or two later, I gave it another test, this time with a hammer and chisel. It held up like stone. And this fellow Jahn—who was an experimenter and an inventor, by the way, and not a mason at all—didn’t use a bonding agent in his mix. I simply had never seen anything like it. I knew I wanted to start using it right away.
Well, this time I was too excited to write, so I called. This is long before the Internet and email, of course. Turns out Heinz, a German living in Holland, didn’t speak English, and my German left something to be desired. Thankfully, Heinz’s wife was there, and she spoke English well; so she played the role of our interpreter. I wanted to know who was the Jahn Mortar distributor in the USA? Where could I buy Jahn’s products? Her translated response to me was: “We don’t have US distribution.”
“Why not?” I wanted to know.
“Because nobody has ever asked.”
From left to right: Heinz Jahn, Cees Turlow, Dennis Rude
I was going to change that. By the end of the call, I’d arranged to meet Heinz at a Stone Show he was attending in Nuremberg. A few days later, I was on a plane to Germany. It wasn’t until I arrived at the visitor center of the Stone Show that I realized I had no idea what Heinz Jahn looked like. The show was packed and there must have been a hundred people in that visitor center. But I must have stood out as The American because Heinz came right up to me with his English-speaking lab assistant, Cees Turlow.
Heinz made quite a first impression. He wanted to talk business at home, so they put my bags in their car and we sped off—right to a liquor store. I watched as Heinz and Cees filled baskets like they had never seen alcohol before. The whole trunk was stuffed with cases of beer, bottles of wine, and boxes of liquor of all sorts. It’s an eight-hour drive from Nuremberg to Holland, and there I was, an American, in the back seat of a car with a trunkful of illegal booze. Just like the internet, the EU wasn’t a thing back then. As we got closer to the border, I was getting nervous. I was thinking that this would be it for me: the border guards were sure to pull us over and make us pop the trunk. I was going to end up in a damned Dutch prison. As we approached the Holland border, my whole body tensed. But Heinz was an old hand at this game. He gave the border guards a casual wave as we approached—at eighty miles an hour! The border guards just smiled and waved back as we blew by and entered Holland.
Jahn Lab, Holland.
The next day we were safe in his lab, applying his mixes in different test scenarios. He had a huge space with every kind of stone in it, and he took delight in showing me how his mixes worked best on all of them. But he’d never say a word about what made his mixes adhere so well.
Dennis Rude working in the Jahn Lab, Holland.
Eventually, he agreed to send me a container load in a variety of colors, but only after I sent him samples of American brownstone, brick, concrete and so on. That was Jahn—he wanted to develop mixes that would exactly meet the characteristic of the stones being patched. When I returned home, I sent him samples, and, a couple of months later, I received my first shipment of Jahn Mortars.
The smallest load I could get was enough to fill half a semi-truck, and I didn’t need all of it, so I tried to get other folks interested. Maybe that way they would buy some off of me. So, I loaded up my trunk and hit the road, showing it to people. Just like me, they were amazed when they saw how superior Jahn Mortars were to anything we used on this side of the Atlantic.
I visited preservation groups, like Restore in New York. I visited magazines like Old House Journal. At the same time, I was starting to get a reputation in the industry, and in 1983 I was invited to speak at an event at the Gettysburg Battlefield. The other speaker that day—there were just two of us—was Frank Matero, who taught building conservation at Columbia University. We hit it off immediately. I told him about Jahn Mortars and what they could do without bonding agents, but he wanted to see for himself. I’ll always remember the two of us huddled under the hatch of my car in the Pennsylvania rain, testing Jahn and other patching materials.
I sent samples of the mixes to his lab at Columbia, but I never got a response from him. A year later, I was in Toronto attending my first Association for Preservation Technology conference. I ran into Frank there along with a conservator from Canada named Martin Weaver. Frank started telling Martin about these mortars. He’d never seen anything like them, he said, and his lab had tried to figure out what was in Jahn, but they just couldn’t. It seemed Jahn had captured his attention, too.
Dennis Rude & Heinz Jahn in Holland.
It just so happened that Frank had been asked to write specs for the restoration of Ellis Island, and we were included as the sole source provider of mortar. I’ve always liked the idea that Jahn came to the United States through Ellis Island. Jahn’s reputation in the US took off from there, and soon it was being used on the Statue of liberty, the Empire State Building, the White House, the US Capital Building, and on and on…
Heinz Jahn was a character—one of the most ornery and interesting men I have ever met. We worked together very closely for many, many years, and we became close friends, but it took another 35 years or so for Cathedral Stone to become the worldwide source for Jahn Mortars.
How that came about is a story for another day.
Author note: Interested in learning more about Jahn Mortar bond strength? Click here for a demo video.
