The Cape Hatteras Lighthouse has seen a lot since the first-order Fresnel lens was first lit in 1870. A number of hurricanes, some monumental nor’easters, being jacked up and put on a giant flatbed to be moved a half mile, even the effects of an earthquake. And through it all that light has kept on shining, warning mariners of the danger of Diamond Shoals.
Of course, the oil used to light the lamp for the Fresnel Lens is now a lightbulb, but the principle remains the same.
But, after all that time and adventures, the lighthouse needs some work, and for the next year or so, one of the most iconic lighthouses in the world will be undergoing some restoration work.
The work will affect the climbing season. If the first phase can be completed in time, there will be some climbing allowed this year, but there are a number of unknowns that make giving a hard and fast date difficult.
The first phase will be returning the interior paint to its original color, and no one is sure what exactly that was.
Over the years a number of coats of paint have been applied to the interior—some of them probably lead-based, which makes removing them more difficult.
The method that is used is to apply citric acid—the acid in citrus fruits—let it dissolve a layer or two, then reapply until they get all the paint off. According to experts on scene, at least six layers of paint have been identified so far. Two of them seem to be the classic battleship gray that the Navy and Coast Guard used from the early to mid 20th century.
Although nothing has been confirmed yet about the original interior paint color, it most likely was a whitewash. The lime-based compound was relatively inexpensive and easy to apply.
The interior work also includes at least one test that has never been done before.
Built very soon after the Civil War ended—construction began in 1868—the Lighthouse Board opted for a double-wall structure—a type of construction that was first used for the Cape Fear Lighthouse.
In a double-wall construction, the outer wall tapers toward the top. That’s visible and easily seen. What is not as obvious is the inner wall. The inner wall is basically a tube of brick that goes straight up and, in the Cape Hatteras Lighthouse, joins the outer wall about 134’ above the ground. From there to the top it’s a single wall.
That form of construction gives a tower like the Cape Hatteras Lighthouse remarkable strength.
To get a sense of how strong it is, the Great Earthquake of Charleston in 1886 was an estimated 6.9–7.3 magnitude earthquake that was felt as far away as Boston, Massachusetts, and New Orleans. James Gregory, lighthouse engineer for the Lighthouse Board, noted, “The force was sufficient to set suspended objects swinging and to overthrow light objects. Of one of the shocks, probably the first, it is said: ‘The tower would sway backward and forward like a tree shaken by the wind. The shock was so strong that we could not keep our backs against the parapet wall. It would throw us right from it…’ The observations were made from the lantern of the tower, 191 feet above sea level.”
The double-wall construction also creates a sealed space between the inner wall and the outer wall at the base.
Although there is no evidence of damage from moisture, the NPS is testing to see if humidity can penetrate the inner wall and if it does, has it caused any damage. It’s not clear what the mitigation steps would be if damage is discovered.
If all goes as is hoped, the first phase will end, probably sometime in July, allowing for some climbing of the lighthouse this year.
The next phase is the one everyone will see—painting the exterior. Testing is already underway for the best way to remove the paint and what is being looked at is interesting.
The most likely solution will be to use dry ice. Sprayed onto the surface, it’s abrasive enough to remove the paint but does not seem to cause any damage at all to the brick. The advantage to dry ice, which is frozen carbon dioxide, is when it melts, it goes away…absorbed harmlessly by the atmosphere.
Ground-up walnut shells are also being tested. Like dry ice, the material will not damage the brick and does not harm the environment.
The second phase will also include repairs to the exterior of windows and the parapet. A start date for that has not yet been announced.