Cleaning Cast Stone
After installing a Cast Stone mantel it should be cleaned with
Muriatic Acid. This should be done after the mantel’s grout
has had time to dry. This process is best left to the mason who
is accustomed to using Muriatic Acid. Gloves should be worn as
it can cause skin irritation. We recommend using two spray or
mister bottles. One should be filled with water and the other
filled with a mixture of 1 part Muriatic Acid and 7 parts water.
If the wall and floors are already finished you should protect
them by taping down plastic drop cloths. Begin by thoroughly wetting
the stone area to be cleaned with plain water by misting. You
should start at the highest point on the mantel and working downward.
Do not attempt to clean the entire mantel at one time. While wet,
spray on the Muriatic Acid, taking care to cover the entire area
being cleaned. You will notice a slight foaming action. A light
scrubbing (with a small nylon bristle brush) while the acid is
working will ensure a more even cleaning. Do not leave the acid
solution more than 30 seconds to one minute to avoid "etching"
the stone. You stop the action of the acid by spraying more water
on the area until clear of acid. Continue this process until entire
mantel as been acid washed. This process may be repeated for stubborn
washing helps remove the whitish film that is a normal result
of the masonry process known as efflorescence. It also helps clean
up excess mortar and the leaching of the mortar onto the stone.
It also exposes some of the silica and gives the stone a beautiful
luster. The washing process does leave the stone wet and should
be allowed to thoroughly dry before sealing.