The 6,000-pound lens in the Jupiter Inlet Lighthouse is getting a checkup in the next few months, but most residents won’t even know it’s happening.
“It’s like the lens has a cavity. We are filling the cavity now to avoid a root canal in the future,” said Lighthouse Operations Chief Steve Kruspe, standing next to the beehive-shaped Fresnel lens 105 steps above the ground.
About $8,000 to pay for the recoating of the putty and possible repositioning of some of the 397 glass prisms in the lens is being raised by officials from the Jupiter Inlet Lighthouse & Museum and Loxahatchee River Historical Society. The work is part of ongoing conservation of the lighthouse first lighted in 1860.
The week-long job will be done in the daytime. Tours will continue and the lighthouse will operate at night.
A lighthouse uses the same process as a telescope, except backward.
The glass prisms in telescopes bend the light from distant objects such as planets, stars and galaxies to make them look closer.
In lighthouses, the glass prisms wrapped around the lamp squeeze the light from 360 degrees into a narrow seven-degree beam that is sent out to sea, visible to sailors with the naked eye from about 14 miles away. The glass prisms in the Jupiter Inlet Lighthouse lens are between 3/8-inch and 2 1/2-inches thick.
Sunlight, heat and humidity have dried out the putty holding the prisms to the brass and bronze frame. Technicians will recoat the putty to prevent further damage.
“When the putty dries out, it pulls away from the frame,” Kruspe said.
If necessary, the technicians will reposition the prisms and add new wedges to hold them in place. Many of the prisms have clamshell-shaped chips on the outer edges, damage from the 1928 hurricane, he said.
“It’s meticulous, methodical work. It’s like surgery,” said Kruspe, 62.
The Lake Worth resident knows that from experience. Every 10 days or so, he cleans the prisms. Cooked bugs are removed with a cotton swab. He gingerly uses an anti-static cloth to wipe the prisms. Latex gloves and a long-sleeve shirt keep his skin and sweat from making contact with the prisms.
“If I touch the prisms, the oils from my skin will leave an imprint when the lens heats them up,” he said.
As Kruspe descends the 108-foot-high lighthouse, he points out the white permeable paint he recently applied to the inside of the red brick used to build the lighthouse. The building takes constant care, he said.