Victor Arnautoff didn’t just paint George Washington onto the walls of the San Francisco high school named after the first president in 1936. He painted Washington into them.

Arnautoff used the fresco technique he had learned from his mentor, the masterful Mexican painter Diego Rivera. First came the arriccio, an underlayer of rough, light-brown plaster on which he would sketch his design. Then came the intonaco, a smooth, white plaster high in lime. While it was still wet, he added il colore, ground colored pigments that gave his murals life. As the plaster dried, a chemical reaction with the air around it called carbonatazione fused the color into the wall.

That is why now, as the San Francisco Board of Education has determined that it is harmful for students to view the murals’ depictions of Washington stepping over a dead Native American and commanding enslaved men on his plantation, they cannot be put into storage or moved to a museum. The murals — 13 individual works spanning 1,600 square feet of the entry hall and main stairwell — are part of the school.

The board first voted to paint over the murals, but after widespread public outrage, it partially reversed itself. The plan now is to cover them with solid panels, although supporters of the mural object and insist any covering must be removable.

This is the story of the layers of history that will continue to exist underneath, whether the murals are covered by curtains, panels or paint.