Nestor Kelebay wrote:
You should be aware that sealing brick or concrete MAY accelerate the
damage. That's because a sealer will only stop moisture from getting into
the masonary if it's getting in through the exposed side that you intend
Often, the moisture that comes OUT of masonary in the form of
efflorescence gets into the masonary from inside the house. It's often
due to warm moist air leaking into exterior walls and the moisture
accumulating as frost all winter. Then, in spring, that frost melts and
causes both efflorescence and potentially freeze/thaw damage at the
exterior surface of the masonary.
In a case like that, sealing the masonary would only make the problem
worse by preventing that moisture from evaporating to the outside as
quickly as possible.
If you are bent on doing something to reduce spalling, you might consider
painting the masonary with a "masonary paint". A masonary paint is a
latex paint that acts somewhat like a check valve when it comes to water.
It allows moisture inside the wall to evaporate out through the paint, but
doesn't allow liquid water from the outside to migrate into the wall
through the paint.
The way masonary paints accomplish this is easy to understand if you
consider the plastic molecules they're made up of as long wires scrunched
up into balls.
There are spaces within each "ball" that something like sand could still
pour through. That's because the sand particles are smaller than the
spaces between the scrunched up wire.
In a similar way, the tangled molecule that comprises a latex paint resin
has spaces between the various segments of the molecule. In masonary
paints, the latex resin is chosen because those spaces are both larger
than the diameter of a single H2O molecule, but smaller than the distance
between H2O molecules in liquid water. Consequently, individual H2O
molecules in the form of humidity can pass through the masonary paint
relatively easily, but not liquid water. Thus, the masonary paint allows
any water inside the water to evaporate out through the paint, but
prevents liquid water (from rain or snow melt) to pass through the paint
into the masonary.
If it were my masonary, I'd paint with a masonary paint before I used a
sealer. The masonary paint will perform the sealing function you want,
but won't prevent evaporation of any moisture already inside the wall.
..in solidarity with the movement for change in Iran.