Laundering Buildings ~ Part II, Old Construction

Words: As you may have read in the May issue article, Part I of this 2-part series, you cannot stuff a building into a washing machine, but the incentive for cleaning has striking similarities to laundering clothes:
  • Improve appearance
  • Discover and restore damage or deterioration
Though we may be told otherwise, human nature does often judge a book by its cover, people by their appearance and a building by its looks. First impressions set the stage for quick opinions, right or wrong, good or bad, and curb appeal can be a deal breaker for a sale - whether someone is trying to sell the building, condos in the building or products and services or entertainment from a company inside. Old buildings present special concerns that tidying up new construction does not entail. Just by virtue of time, more dirt, mildew, stains and unknown and unwanted pollutants may have collected on the surface. There can be unseen deterioration and even potential instability in the structure, which are camouflaged by decades of neglect. While patina is often connected to the green film on copper and bronze, it is also defined by Merriam-Webster as: "a surface appearance of something grown beautiful especially with age or use, [example] the beautiful patina of this antique table." An early consideration in cleaning an old building is the patina, which may have been planned by the architect and is now an appealing characteristic of the aging exterior. Careful analysis of the natural aging of masonry materials and the desired outcome is imperative at the outset. Like today, builders of yesteryear often employed a mix of materials; so different masonry products may appear on the facade, along with non-masonry components. Brick with stone trim was popular, and decorative features may not be masonry at all. Many historic brick structures were painted to safeguard porous bricks and sandstone or to hide imperfections or a mix of masonry products. Others may have been painted to hide poor workmanship or repairs, sort of like gravy can mask the occasional mishap in the kitchen. Old buildings present a whole set of unknown variables, things that are discovered along the way like multiple coats of different kinds of paint or stone that looks real but is cast concrete. "I can’t guarantee much in my line of work, but I can guarantee that you will always find a surprise," declares Sarah Holder, preservation specialist with PROSOCO. "The exact same buildings - same substrate, same construction year, same materials, same environment - can be across the street from one another and have very different soiling, based on maintenance and previous interventions. Things can vary significantly, that’s what is great about restoration; you will never have the same project; it is always different." Delving into four basic questions and carefully gathering and evaluating information is the best way to experience a successful outcome to laundering a structure more than 100 years old.
  • WHAT are you cleaning?
  • What are you cleaning OFF?
  • What are you cleaning WITH?
  • WHO is cleaning?
  WHAT Are You Cleaning? As with any cleaning job, the first piece in the information puzzle is the material with which you are dealing. Old buildings may have been constructed with any of these materials or a combination:
  • brick
  • stone (limestone, marble, granite, sandstone top the list)
  • stucco
  • architectural terra cotta
  • artificial cast stone (imitation stone)
  • pre-cast concrete (imitation stone)
"During colonial times," explains Holder, "the raw material for brick production, clay, was widely available. The manufacturing process varied slightly throughout time, ranging from sun-baked, low-firing, to high-firing processes, but each process produced essentially the same, recognizable form and color of modern day clay bricks." Fletcher Smoak, former CEO of Old Virginia Brick Company, which worked extensively on buildings at Yale, William & Mary and the University of Virginia, cautions that old brick on the same building can have different hardness characteristics. "Lighter color bricks often seen in an arch over a doorway and windows, for example, are softer and therefore easier to grind to have crafted the arch." "Practically every state has a limestone formation, and limestone was easily accessible when transportation and shipping were limited and expensive," Holder continues. "One of the most widely used limestone is the Bedford, or Indiana, Limestone." Along with limestone, marble, sandstone and granite were quarried and cut for building material. Not only does each stone have different chemical and geological compositions and hardness and porous attributes, but even among the stones themselves, reactions vary. Some sandstone, for example, will tolerate an acid cleaner and others are damaged by it. "The popularity of each masonry material varies greatly based on the location, environment, trends in manufacturing, date of construction and so on," Holder points out. "We start many of our presentations with a 'know your stone' section, going through categories of masonry materials, such as natural stone and man-made clay materials." Once the masonry and non-masonry materials have been identified and documented for composition and condition, it's time to analyze the stains and gunk adhering to the building.   What Are You Cleaning OFF? Dirt resides everywhere, and the blowing sands of eastern beach communities and red Georgia clay are very different from arid desert ground in Nevada and varying degrees of saline, acid, clay, silt and a host of elements and minerals making up the unwanted soiling and stains on a building. Industrial and urban pollution, weather patterns, site orientation and environmental conditions impact buildings in various ways, even buildings in the same community or on the same street. The common bond, however, is the prudent measure of regular maintenance and care for old buildings to safeguard appearance and correct and prevent deterioration of masonry structures. Besides good ol' dirt, there are many things, which can negatively impact a building's exterior:
  • chemicals
  • pollution
  • water
  • vegetation
  • efflorescence
  • metallic stains
  • fungal growth
  • graffiti and more.
"Most deterioration is caused by prolonged exposure to water-related sources," states Holder. "But, deterioration can be caused by mechanical damage, anthropogenic factors such as inappropriate cleaning or previous treatment, inherent vice (the material itself was flawed or used in a way that lead to advanced deterioration), carbon crusts, acid rain, etc. Location can play a factor in deterioration, or the environment, or deferred maintenance of structural elements." Ivy and plant materials differ from metallic stains, graffiti and fungal growth, and one building may have as many stains and dirt residues as kinds of materials in the structure. Extra attention may be needed in hidden-from-view places like sheltered spots under eaves, window sills and decorative features, as well as back corners and walls where trees and shrubbery may have grown unattended.   What You Are Cleaning WITH?  The mantra for cleaning anything, clothes and buildings included, is to use the most gentle cleaning agents and methods possible to get the job done well. Old buildings, especially ones that have received little attention across decades and centuries, may be fragile with deterioration. There are two basic ways to remove stains and dirt. You must wash away the offending material and/or destroy the bonding component between the soiling agent(s) and the masonry. Water is great for cleaning all types of masonry and clothing, but it's generally not enough by itself. If it were, you might be able to depend on rain alone in parts of the country where it rains often. Water is great for loosening dirt, but too much can corrode metal anchors and penetrate surfaces. Depending on the size of the building, millions of gallons of water are needed, so run-off needs to be considered, along with water analysis for iron content and chemical additives. High iron presence in water can stain light-colored stone, and that's counterproductive to the objective of cleaning in the first place. "We always stress the need to test. It is beneficial to test your masonry to identify the substrate and its composition, then analyze the staining (or contaminants) and complete a performance evaluation of selected cleaners," Holder contends. "This allows for testing to be completed in a controlled environment and for more advanced analysis. We also recommend on-site testing, always. Testing and on-site mock-ups allow you to test cleaning solutions, determine appropriate dilution rates, evaluate dwell times, select appropriate equipment and site restrictions, assess the cleaner in that specific environment and figure out the sequence of events for the project." Abrasive cleaning is never recommended for old buildings, and steam cleaning has fallen out of favor because it creates visual impairment and can harm the operator. Muriatic acid even diluted can damage surfaces as well. Sand blasting or grinding methods may cause unwanted disturbance in terms of flaking or destroying already fragile materials. Diedrich Technology’s advanced masonry cleaning products are specifically formulated to safely – and cost-effectively – reveal the beauty underneath all the built-up grime and paint. Jeremy Douglas, director of architectural services for Diedrich Technologies, says: "There are many products in development and several environmental requirements on every level ~ local, state and national. We're working on products with lower levels of acid and some in gel form so they can sit longer and are not as aggressive a cleanser." He also recommends a pre-rinse product for every cleaning endeavor. "Masonry is super porous, and if you don't add a layer of protection at the outset, the cleanser will be sucked into the masonry. You want to keep chemical cleansers at the surface." With a broad array of pre-mixed cleansers on the market and on-going R&D in the halls and laboratories of major masonry cleaning products companies, it's not necessary to re-invent the figure-it-out-yourself wheel. Diedrich has an impressive line of cleaning products for paint, graffiti and all manner of restoration projects. According to its website: "Diedrich detergent processes are approved for cleaning buildings on the National Register of Historic Places and are ideal for countless historical restoration challenges from clay masonry cleaning to paint removal." PROSOCO products have been used extensively, for example, on Smithsonian's Freer Gallery of Art, the U.S. Capitol Building, the Pentagon and Frank Lloyd Wright houses around the country, to name just a few. Sarah Holder thrives on restoration and consultation with clients using their products. Nick Blohowiak, national sales manager – masonry, SPEC MIX, a Quikrete Company, reiterates the value of testing in a lab and on site. "If the solution does not work properly, there could be stains and/or damage to the surface." The whole goal of historic preservation and cleaning of any old building is to restore its materials in terms of both function and aesthetics.   WHO is Cleaning?  Because of the vast assortment of materials, cleansers, procedures, equipment and supplies, serious old building laundering should be entrusted to reputable professionals. Not only do they understand water pressure, masonry composition, personal safety, cleaning agents and residue collection, but also they know or know how to find local, state and national permits, environmental rules and process regulations. Seek references, look at comparable buildings they have cleaned and review every detail of their intended process and cleaning agents. There are copious variables in old building work, and, as Holder so aptly observed, always a surprise. Additionally, "it's a very fluid process from beginning to end, starting with the experience and comfort level of the contractor in this type work," Douglas explains. "There's weather and temperature patterns that impact the whole cleaning process. An exterior wall temperature of 40 degrees in the morning may respond quite differently to the same cleaning agent when it's 80 degrees in mid-afternoon. A product, which dries in four or five minutes at one temperature, may linger 15 minutes another time of day. A light breeze around a high-rise in an urban environment can require special netting or air barriers." A professional cleaning company is a combo environmental, chemical, water, masonry and regulation expert, or they know how to build a team with knowledgeable specialists. "There are many advancements in the cleaning chemical world including environmentally-friendly formulations specifically designed for masonry units and common stain problems. All masonry cleaning requires highly skilled workers who are specifically trained in masonry cleaning techniques," says Blohowiak. "A great looking masonry project can turn bad if the cleaning process is not appropriate. Overly aggressive cleaning practices can further age the units and mortar joints. They can also expose aggregates and disturb patina, changing the designer aesthetic vision for the project."
Words: Joanne M. Anderson Photos: Masonry Magazine
Joanne M. Anderson is a freelance writer and magazine editor with more than 1,000 articles and blogs in print. She especially enjoys home improvement and building topics. ------------------------------------------------------------------------------------------------------ SIDEBAR: We find that it is critical to understand the masonry you are working with before you select a cleaning technique; otherwise you can cause irreversible damage, or at a minimum, are unsuccessful in cleaning the masonry. ~ Sarah Holder, preservation specialist, PROSOCO      
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