'Absolutely Horrible'
“Absolutely horrible.”
That’s how Jeff Lucas described the limestone façade
around the entrance of the brand new conference and event center at
the recently restored French Lick Springs Hotel, French Lick, Ind.
Mr. Lucas is a partner in the manufacturer’s rep
firm J.N. Lucas & Associates, Hammond, Ind. He’s also an expert in
masonry and stone architecture restoration cleaning. Mid-Continental
Restoration Company’s Indianapolis-based Indiana branch called him
in Spring 2007. They wanted advice on how to fix the “absolutely
horrible” limestone façade.
What had happened, Mr. Lucas explained, was that the
contractor used a runny mix of mortar applied from grout bags to
fill the joints between the limestone panels attached to the new
convention center’s CMU backup.
Some of the slurry ran down the face of the
limestone.
Workers tried to wipe it up, but only managed to
smear it around. They created a huge ugly mess, Mr. Lucas said.
“No one knew what to do or how to get it off,” he
added. “So they compounded the error by leaving the mortar on the
limestone face for several months.”
Eventually, the hotel developers called Ron Pertl,
Mid-Continental’s Indiana branch manager, to see if he could clean
the blemished limestone.
In 2006, Mr. Pertl’s group had completed a
successful exterior restoration cleaning of the historic hotel the
new convention center was attached to, Mr. Lucas explained.
“So it was natural the developers would turn to them
for help on this,” he said.
“I wasn’t sure we could get the cured mortar off the
limestone without damaging it,” Mr. Pertl said. “So I called Jeff
Lucas. He recommended several PROSOCO products to test.”
Mr. Pertl and Mr. Lucas settled on Sure Klean®
VanaTrol®
to take off the
hardened mortar.
Though originally created for new construction
cleaning of clay brick
masonry, Vana-Trol® has successfully
cleaned new and historic
limestone facades –
including the Pentagon’s
limestone exterior, both
pre- and post-9/11.
VanaTrol®
takes its unusual
name from a
contraction of “vanadium” and “control.” Many
types of light-colored
clay brick contain naturally
occurring vanadium, a
metallic salt. Raw acids used
by the un-informed to
clean excess mortar on light colored
bricks often dissolve the
salts. That mobilizes
ugly green or brown
stains across the brick face.
Sometimes even proprietary cleaners can have that
effect.
PROSOCO developed VanaTrol®
with special
blends of
surfactants and inhibitors, combined with tiny amounts of
purified, food-grade
acids to remove the mortar without mobilizing the stains.
That formulation makes VanaTrol®
highly effective
on sensitive
limestone architecture, both new and historic.
Unfortunately, as both Mr. Pertl and Mr. Lucas
pointed out, the mortar stains had been left to harden on the
surface for months. Typical VanaTrol® procedure calls
for cleaning within 14 - 28 days – before the mortar has a chance to
reach its intended rock-like hardness.
Done within that recommended window, VanaTrol® can be diluted
with fresh water up to 1 part cleaner to 10 parts water.
Professionals like higher dilutions because they are easier on the
stone, and more cost-effective.
But this mortar had hardened beyond the 28-day
limit.
A dilution strong enough to dissolve it could risk
etching the limestone as well.
Testing revealed that Vana Trol®,
prepared at a higher concentration than is typically recommended,
was required to get the job done. Even then, careful brush
application augmented by vigorous scrubbing was needed to mobilize
the hardest mortar while minimizing adverse effects on the
limestone.
Following successful testing, Mr. Pertl’s crew
attacked the dried mortar smears, working in drops 16 feet high and
30 feet long. They soaked the stained stone with water, brushed on
the diluted cleaner, and scrubbed. They let the VanaTrol® do its work for 3
– 4 minutes, then flushed the spent cleaner and dissolved mortar off
at 500 psi.
It took 2 weeks to restore the approximately 3,000
square feet of limestone. At the
end, the stone looked brand new – “which it is,” Mr. Pertle said,
“so that’s how it’s supposed to look.”
Everyone involved was ecstatic that the stubborn
stains had been removed, Mr. Pertle said. Perhaps the happiest was
the mason who’d put up the stone units.
“If we hadn’t been able to clean the limestone, plan
B was to tear it down and start again,” Mr. Pertl said.
“And it was going to be at the mason’s expense.”
Back to top
|