[Illustration: The Renwick Gallery, made of brick and sandstone, was
completed in 1859.]
This building of brick and sandstone, completed in 1859, is interesting
from a stone preservation point of view. The decorative sandstone panels
were badly deteriorated, so in 1968 the panels were saturated with epoxy
to strengthen them. This treatment actually accelerated the
deterioration because when water penetrated behind the epoxy-filled
area, large portions of the treated panels spalled off. A second
renovation attempt was therefore necessary two years after the first,
and the present panels are cast sandstone. A post of the original
sandstone stands at the southeast corner of the building.
[Illustration: Casts of ground sandstone and epoxy replaced the
original carved sandstone decorative trim at the Renwick Gallery
when a first attempt to preserve the carved stone failed.]
The next part of the tour begins at 15th Street and Pennsylvania
Avenue S. To get there, walk east along Pennsylvania Avenue, past
Blair House and between Lafayette Park and the White House. Lafayette
Park has a number of bronze statues that have been cleaned fairly
recently. The White House is built of sandstone that was painted
white; the paint was used in part to improve the durability of the
stone. After you pass the White House, you will come to the Treasury
Building. Turn right onto 15th Street and walk south, towards the
Washington Monument and the Mall. The total distance from the Renwick
to the corner of 15th and Pennsylvania is about three-fourths of a
kilometer (half a mile).