More about bonding agents
I am having my 1969
So. Calif. house restuccod and the Sub wants to use a cement type glue
to glue (Crete-Weld) over the old painted stucco. I have been told that
sandblasting the old stucco is vital for a good bond, he feels that he
can get away without sandblasting the old stucco and just applying the
glue product directly over the old painted stucco. Can you please
on this issue?
I got sued when a house we did this
popped off 4 years later. Jobs we did 10
years ago are now popping off. Weld
dissolves in water. Stucco
isn't waterproof, and is porous. Water will
dissolve the weld crete.
It may last longer in Southern California
to the lack of humidity, but I doubt much longer.
I just redid a patch (for free) I did
a friend's house 9 years ago that was popping off. The way
plaster weld and euco weld work, the surface dissolves
with the wet plaster (or cement mortar).
the mortar sets, it all dries together
forming a chemical bond. This works fine
indoor plaster with a warning
on the can not to be used in wet areas.
me here. It has cost me a lot of
money and embarrasment.
Weld-crete, plaster weld and euco weld say
on the bucket not intended for
wet areas such as showers. The outside of a
gets wet, too. These bonding
agents work fine for interior plastering,
fail when used for exterior stucco.
We have torn off loose stucco on buildings
this way. It makes me sick to
ride by buildings we did 10-15 years ago
have loose stucco and maybe some
band-aid patches. I didn't know any better.
Acrylic bonding agents work great for
on unpainted porous surfaces
such as concrete, old stucco (unpainted),
They are used in swimming
pools. The directions on the bucket says
with mortar and not paint on first.
The acrylic mortar mix can be troweled on
even painted on with a brush, and
left rough for the application of a brown
or just a finish coat.Examples of these are Acryl60, Flexcon or
I worked with an old plasterer years ago
showed me how to bond cement
mortar to concrete using a Portland cement
Pure portand(no sand) is
mixed with water and painted on. First the
is wet down. Second,
the cement paste is painted on leaving the
rough. The paste sets instantly
when it hits the concrete, and then starts
dry. A scratch coat of mortar must
be troweled on before it dries. One
can paint a small section at a time,
and then scratch mortar on right away, or
can go ahead painting and the other
This method was used in swimming pools
ago, and is still used in foreign
countries. I saw this done when I was in
Thick stucco ceilings were applied
to concrete slabs with no failure. If they
it on a ceiling, I trust it, too.