Historic Restoration on the Jefferson Memorial

Laser ablation safely removes contaminants without impacting the integrity of the substrate. This is essential for historic restoration projects. It’s for this reason that Adapt Laser has provided cleaning systems for projects ranging from local municipality buildings to the Egyptian pyramids. And, when a mysterious biofilm plagued the top of the Jefferson Memorial in Washington D.C. our customer, CSI/Evergreene — alongside other laser cleaning experts — were called in to solve the problem.


Since 2006, a dark greenish-black biofilm — made from bacteria, algae, and fungi — has slowly begun covering the dome of the Jefferson Memorial. This mysterious contaminant is likely due to weathering, but the exact cause is unknown. While the bacteria doesn’t seem to be harming the memorial, it does diminish the aesthetic and causes the once pristinely white dome to appear blotchy and dated.

Cleaning the dome using regular methods doesn’t return the memorial to its restored glow, and media blasting options would damage the dome — reducing its lifespan. With laser ablation, the biofilm is safely removed, and the largest lifespan of the memorial is maintained.


In 2017, CSI/Evergreene — in conjunction with other laser experts — began testing laser solutions on a 1,000 square foot strip. What they found is that the biofilm was not only safely removed, but the laser solutions restored the surface to its previous prestige. While any environmental decay wasn’t reversed, the cleaning helped preserve the dome surface and protect the lifespan of the memorial.

Unlike previous attempts of cleaning, the testing strip remained white, and no biofilm returned. This is a step forward in preserving the Jefferson memorial and returning it to its pre-biofilm glory. But, the completed restoration project will take time. Only two square feet are properly cleaned each hour. This is to ensure that the substrate is protected and all contaminants are properly removed.

Adapt laser has provided the solutions to work on various historic restoration and conservation projects throughout the years — including precious buildings and other locations for RJW-Gem Campbell Stonemasons Inc and CSI/Evergreene. For more information about our customer’s role in the 2019 Jefferson Memorial restoration project, read the full story here.