Recently we were contacted by Matt Kuehne of the Pensacola Lighthouse Museum and asked to do some evaluation and potential restoration of the antique metalwork on the lighthouse.
Renaissance man has done quite a bit of restoration and repair of antique wrought iron metal work over the years and we were particularly excited by this project because of it’s historic significance… not to mention the romance of all things nautical.
The first stage in the process of a restoration project such as this is to identify the type of metal which we are working with. All irons and steels are simply iron ores with different carbon content and the level of carbon in wrought iron is very low. Its fibrous appearance is because of the oxidized metal impurities, or slag in the iron. Antique wrought iron work is usually identifiable by a lack of welding at the connections as compared with steel. By the time welding was invented wrought iron had gone out of style in favor of the stronger modern steels.
Back in 1859, when this lighthouse was built as a guiding beacon to ships near the Panhandle’s coast, the stairs were probably fashioned from iron ore processed in a bloomery, where the hot iron would be fashioned into sheets or rods of different sizes and shapes after having been drawn from the smelting oven. The iron would then be re-heated until glowing red hot, held with heavy iron tongs and worked gradually into shape with a variety of pounding, shaping and turing tools.
Antique wrought iron is actually more similar to cast-iron than steel and though not as strong as steel, is more resistant to corrosion. But 150 years of salty, humid air will certainly take a toll and unfortunately the metalwork in recent years had been poorly maintained and we identified many issues to be addressed. After confirming that the lighthouse material was in fact antique wrought and cast iron, we made a priority of repairing the broken railing sections in the crows nest at the lighthouse’s top.
The next phase was to identify all of the issues weakening the metalwork on the lighthouse and propose a strategy to the lighthouse keepers. Significant problems were found at the joining of the antique cast iron stair treads and the brick lighthouse walls, where the limestone in the mortar between the bricks caused condensation which lead to significant rusting.
The approved recommendation included a full scraping and removal of loose rust flakes and chunks, and a rust treatment with a tannic acid-based rust neutralizer, followed by weld repairs and replacement of any metalwork that was beyond repair. Finally we treated every inch of the metalwork with a coat of red rust preventative oil-based primer and a topcoat of an oil-based black enamel.
With proper maintenance the restored antique wrought and cast iron metalwork at the Pensacola Lighthouse should hold up for at least another hundred years.