Why did DHS Secretary Kristi Noem paint the border wall BLACK?

DHS Secretary Kristi Noem went to the border on Tuesday, where she participated in painting a portion of the wall black. She wrote on X that "Today marks seven months of @POTUS Trump’s second term. When we got to work, America faced the worst border crisis in history. Today, that crisis isn’t just under control— it’s been obliterated.This wall is part of the difference. Too high to climb. Too narrow to squeeze through. And now, at the President’s direction, it will be painted black— so hot to the touch that criminal illegal aliens won’t even try."