Fall 2007

All better now – PROSOCO products helped repair the appearance of the damaged limestone facade of the conference and events center at the recently restored French Lick Springs Hotel.
-- Photo Courtesy Ron Pertl

 

Plan B – This limestone wall, mottled and discolored by smeared slurry hardened from being left on too long, would’ve had to be torn down if it couldn’t be cleaned. Thanks to PROSOCO products, it never came to that.– Photo Courtesy Ron Pertl

 

'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.”



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In This Issue:

Floored! (cover story)

'Absolutely Horrible'

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©2007 PROSOCO