Washington state lawmakers approved funding to clean the capitol dome, but it could get dirtier before it gets scrubbed clean.

Lichen, a combination of algae and fungus, is giving the dome its dirtier-than-usual look, according to Capitol Campus Architect Chris Gizzi.

“It’s about the darkest the stains I’ve ever seen,” said Gizzi.

He said that might be attributed to how the dome was last cleaned in 2012. Gizzi said the state chose not to use the traditional chemical cleaner, which was thought to have damaged the capitol’s sandstone.

If Governor Jay Inslee signs the budget into law, the work could start late this summer. But Gizzi said with the logistics involved in the cleaning, it might not happen until the summer of 2019.

“We try to use the best science that’s available to us and the best techniques, that’s why the process takes long,” said Gizzi.