Hydroclean Newsletter


Spring 2014 - Our 33rd year in business.

The economy is starting to show some signs of life, especially in the service sector where most of our market resides. Capital investment is way down and a lot of cash is on the sidelines just waiting for some assurance that the economy is really moving forward again. We have seen some improvement this season and I hope it portends a positive trend upward. Good service and an aggrissive sales program will get us all through this major bump in the road. Please let me know if Hydroclean can assist anyone in any way.

Tom Rudder



Procedures for the Cleaning of Interior Stone.


Our industry is generally involved with the cleaning and restoration of building exteriors. One hears very little about the cleaning of interior substrates. This article is dedicated to the cleaning of the limestone, marble, granite, brick or terra cotta found in building interiors. Architects have always appreciated the color and architectural accents that interior stone can bring to building lobbies and other impression rooms within the building. Stone is used on floors, baseboards, wainscots, or on entire walls and ceilings. Although interior substrates do not have to endure the ravages that weather imposes on exterior stone, they do have their own contaminants that can compromise their beauty.


Interior contaminants are mostly carbon based and come from misplaced hands, shoes and hair. Soot from old oil or coal fired heating systems is another carbon-based contaminant that gets deposited on interior stone. It was not that long ago that people were allowed to smoke within a building and thus more carbon.


Carbon-based interior contaminants are generally easy to remove and will react best with a mild alkaline cleaner. If a given cleaner is capable of removing the dirt and is mild enough, the cleaning can be accomplished with a one step process. If a stronger alkaline is required, then the cleaning process will require a second step that will consist of a mild acidic after wash. The acid after wash will perform two functions. The first is to remove any inorganic material (metals) that may be on the surface and the second is to neutralize any residual alkalinity from the first step. For polished stone use only mild cleaners. The polished surface limits the porosity of the stone so most of the contaminants stay on the surface and are easily removed. Exercise extreme caution using the stronger cleaners on surfaces that have been honed to a polished finish. The stronger cleaners may compromise the finished surface.


The best results for interior cleaning are achieved using the following process. First perform some test cleaning areas to determine the proper cleaning product and the appropriate dilution ratio of the product. Give the sample areas plenty of time to thoroughly dry and then observe the results. Make sure, through testing, that the end result is what is desired before commencing on the project. The manufacturer of the cleaning products can have their representative assist the contractor/architect/owner in determining the correct product and its dilution. After applying the cleaning product and waiting the proper dwell time, the stone must be rinsed. In all cleaning projects the rinse cycle is just as important as the choice of a cleaning product. For interior cleaning the best results are achieved by using water pressurized through an airless sprayer that is capable of 1500 psi and a gallon per minute. The sprayer's gun will deliver the spray in a 15 to 25 degree fan making the rinse even and controllable. The effluent from the rinse process can be easily collected with one or more wet vacuum cleaners. The entire process is an efficient, controlled closed loop system.

The pressurized water rinse is necessary to reach into the pores of the stone and to remove all traces of the cleaner and the contaminants.


Workmen who have experience using the cleaning system outlined above will have little trouble with the protection of contiguous areas. Normal common sense applies. If there is a rug at the base of the wall that is being cleaned, it must be removed or at least rolled back. The floor or wall electrical outlets must be covered. Any artwork or signage must be removed and any wooden surface must either be protected or removed. The wet vacuum cleaner described above will easily be able to control the effluent.

It is always best for any cleaning work to be performed after normal working hours when the workers will have the building to themselves. Although interior cleaning products and the application and rinse process is generally non-hazardous, it is always preferable to keep the building's occupants away from the work areas. Even a mild smelling cleaner can cause some people to have unrealistic concerns and to complain.


The exterior of a building will dry fairly quickly after cleaning. It has the wind and the sun helping the moisture within the stone to evaporate. Not so with interior stone. The air pressure of the ambient air within the building is relatively high and constant, so it will take some time for the residue of the rinse water to evaporate into the building's atmosphere. In the meantime, due to the varying porosity of the stone, it may dry unevenly. The areas around the substrate's joints will hold more moisture and might, at first, look darker than the surrounding stone. The impression can be that it was incompletely cleaned and the temptation will be to re-clean the wall. But it is best to just leave it alone and give the surface the time it needs to dry. Depending on the humidity, the season and the building's air handling system, it may take as long as three months for interior stone to completely dry.


The results of a properly managed interior cleaning program are generally very satisfactory. The advice to follow, as on all building cleaning projects, is to use experienced contractors and cleaning products from manufacturers who have a long demonstrated history of successfully cleaning stone.


Thomas H Rudder




Philosophy of chemical formulation


Manufacturers of restoration cleaning products as well as restoration contractors have had to deal with much misunderstanding over the design and safety of chemical cleaning products for masonry. Even with the array of sophisticated building cleaning products on the market today, we are unfortunately still dealing with the unsavory reputation that the building cleaning industry earned during the 1950's and 1960's when building exteriors were cleaned using raw hydrofluoric acid and the strong alkalis that were, and still are, used as floor strippers. Many beautiful building exteriors were compromised during that era. The industry has come a long way, but we are still fighting the connotation that chemical cleaning is unsafe for historic substrates. I would like to attempt to review the process of how a product for cleaning stone is designed and formulated. The purpose is not to offer a definitive course in chemistry, but to give the architect, contractor, historical consultant and building owner a general understanding of the thought process that a modern manufacturer uses to develop safe, effective cleaning systems for masonry substrates.


The first step in designing a cleaning product is to identify the contaminants that we are trying to remove. In large metropolitan areas masonry buildings have some carbon build-up, various salts, silicates and oxides from the incomplete combustion of fossil fuels. The over simplified chemistry of fire is that the exhaust (smoke) is acidic and the ash is alkaline. So when the exhaust from power plants and automobiles is deposited on buildings we have, in addition to the carbon contamination, sulfur oxides from the incomplete combustion of high sulfur fuel oils and nitrogen di-oxides and tri-oxides from the incomplete combustion of gasoline. Reintroduce moisture in the form of humidity or rain and these oxides form sulfuric acid and nitric acid, both of which are extremely detrimental to masonry substrates. Other exterior contaminants include various metals such as magnesium, iron, copper, aluminum and other metals and their salts that are inherent to our industrialized economy.


Most manufacturers attack the contaminants found on brick, granite, sandstone, limestone or marble building exteriors with water-based cleaners that either have an acidic or an alkaline pH. The acid(s) or alkaline(s) in the formulation perform various functions necessary to break the bond of the predetermined soils from the stone. Wetting agents are added to the formula to release the surface tension of water and thus allow the water based cleaner to penetrate into all areas of the contamination. The job of emulsifiers is to hold the contaminants in suspension until the rinse cycle can be applied. Good emulsifiers will also help to insure that the product will rinse well which will assure the removal of all traces of the cleaner/contaminant effluent during the rinse cycle. Buffers are used as a safety factor and their job is to retard the reaction of the acids or alkalis. Even though some products necessarily use a percentage of acids or alkalis in their formulations that are considered, by themselves, to be very strong, the buffers serve to retard the reaction to the point that the formulation is safe for use on masonry. Thickeners give the formula some body and that allows the product to hold on vertical surfaces. Some products have humectants that attract moisture to help the product stay wet until it is time to rinse.


Brick, granite and sandstone can generally be cleaned using a one step, single product process that can remove both the organic (carbon) and inorganic (metals) contaminants from the building. The rinse cycle, which is a separate but equal part of the cleaning system, serves to both flush the product/contaminant effluent from the stone and to neutralize the stone so that upon completion of the rinse process the substrate is left evenly cleaned and with a neutral pH.


Limestone and marble are comprised of the more sensitive calcium carbonate, so these building substrates usually are cleaned with a two-step process. The first step is to apply an alkaline cleaner that will loosen the organic (carbon) based contaminants. After a dwell time the effluent is rinsed and then a mild acidic product is applied and rinsed. The acidic product will perform two functions. The first is to remove the inorganic contaminants (metals) and the second function is to neutralize any residual alkalinity left from the first step. It is important that any building be left with a neutral pH, but as calcium carbonate buildings are basically alkaline to begin with, we do not want to leave any excess alkalinity imbedded in the pores of the stone. Calcium carbonate based substrates are extremely sensitive to harsh cleaning methods, so great care must be taken when choosing acid or alkaline constituents for their cleaning products.

Interior contaminants are much less complicated to clean and generally consist only of carbon-based soils such as hand sweat, cigarette smoke and soot from the building's heating system. Generally all that is needed is a mild alkaline cleaner that can emulsify the soils and then a thorough rinse using a rinsing system designed for building interiors.


Some building cleaning projects require the removal of paint. The buildings may be totally coated with paint or there may just be some graffiti. Paint removal requires a different type of chemistry that will be discussed in a future article.

Manufacturers of chemical cleaning products will provide detailed instructions on the proper use of their products. These instructions must be followed exactly. Depending on the individual formulation, the application of the product, the dwell time and the rinse process may vary from manufacturer to manufacturer. So for the best results, the contractor must pay close attention to the outlined procedures. Each product is designed to safely emulsify building contaminants and hold them in suspension until the rinse cycle can be applied. The rinse cycle is just as important as the application of the cleaner. Its function is to flush all traces of the contaminant/cleaner effluent from the stone and to leave the stone neutralized. The rinse cycle must be accomplished in a timely manner and must be performed slowly and deliberately thus assuring a complete rinse of the substrate.


The rinse process must have a certain pressure and volume ratio to accomplish the task of thoroughly rinsing the stone. The hitting force of water is determined by both the volume of water and the pressure at which the water is delivered to the surface of the stone. Any good cleaner is designed to migrate into the stone in order to emulsify the interior soils as well as the surface soils. Therefore the rinse cycle must have the power to flush into the substrate to remove all traces of the contaminate/cleaner effluent. Water hose or other ludicrously low pressure/volume combinations will not adequately rinse a building unless the rinse process goes on and on poring great volumes of water into the building. Most non-friable building substrates can be safely cleaned using a pressure of 1500 to 1800 pounds per square inch (psi) and a volume of 4 to 5 gallons per minute (gpm). The water/pressure rinse combination is delivered through a high-pressure water gun with a 15 to 25 degree fan tip. This pressure/volume will work with brick, granite and most sandstones. It will also safely rinse most calcium carbonate based limestone and marbles. These pressure/volume combinations have been successfully used for many years and will not harm the substrate or any sound mortar. In addition to assuring a complete flush of all traces of the cleaner, these pressure/volume combinations play a vital role in assuring that the building is evenly cleaned and that the rinse effluent is dilute enough to enter the City's sanitary sewer system.


In the case where a substrate is extremely friable, lower pressures may be necessary. It will be the contractor's responsibility to be sure that the building has been thoroughly rinsed. The contractor can test for any residual acidity or alkalinity remaining in the building's substrate by using pH paper, which should be on every building cleaning jobsite. The objective is to leave the building's surface as close to a neutral pH as possible.


A properly cleaned building will display a symmetry of evenly cleaned stone that will showcase the natural color and hue of the masonry. The cleaning will have been accomplished without altering the surface or the porosity of the stone. Once completed, it will accurately represent the original architect's atheistic design and intent.


Remember that cleaning a building requires the adoption of a system that includes the choice of the right cleaning product, the right pressure/volume rinse combination and the right contractor who will perform the work. Compromising any of these three elements could compromise the entire cleaning project. The best safety net is for an owner/architect/building manager to insist on using experienced product manufacturers and experienced contractors both of whom should have a long demonstrated history of cleaning historic buildings.


Thomas H Rudder





Observations Of A Tragedy's Aftermath

This was my first trip to New York since the September 11 attack. I had to visit customers and deliver some product, and I wanted to see the City and make observations. One of the stops was at the Tweed Courthouse, which is located approximately four blocks from "Ground Zero". I thought maybe I could take a walk down a side street and catch a glimpse of the site that I had seen and visited so many times in the last twenty plus years. Unexpectedly, what I got was an "all access" pass right to "Ground Zero".

Coming into the city from the north, I was surprised at how light the traffic was. Traveling in and out of New York City has always been a traffic nightmare and had been getting worse each year. But today the trip was a breeze until I got to the toll bridge that spans an estuary of the Hudson River and was an entry point to the island of Manhattan and the Henry Hudson Parkway. Just prior to the bridge, I encountered my first backup as traffic was divided into two columns that had to go through the City's initial security checkpoint. Two, very serious, New York State troopers stood by and closely observed each car that idled by. They were obviously profiling and looking for any reason to stop and search or to question the driver.

I apparently looked OK and was allowed to proceed into the City. Once again the Henry Hudson Parkway was moving smoothly and I made quick time down to West 57th Street. From there I took a right on 9th Ave and headed south down to West 39th Street where there began to be more of a uniformed police presence. My first customer was located near West 39th and 10th Avenue and I had to get a police officer's permission to pull into their loading dock.

I found that everyone in New York has a story to tell and it started for me with my first customer. They are also in the specialty cleaning business and along with many other service contractors were called on to begin site cleanup the day after the attack. The streets around the WTC site were deep with cement dust, paper and other residual debris created from the collapse of the buildings. Their job was to pickup, shovel up and sweep up everything on the street and put it all into plastic bags. The stories of what they were finding ranged from large bank checks, to personal effects of the victims, to pieces of human remains. The violence of the initial attack, coupled with the heat of the fire and the impact of the energy created when two 110-story buildings collapse into themselves, apparently vaporized much of the concrete, twisted the steel I beams, which once were the building's main source of support, and made the prospect of finding anything or anyone intact very remote.

From the West 39th and 10th Avenue stop I had to continue downtown by cab, as only commercial vehicles were allowed further south. My next destination, The Tweed Court House, was on Chambers Street and was just about at the end of the line for non-emergency or non-disaster site related vehicles. As I said the Court House is only about four blocks from "Ground Zero". Once again, everyone had a story to tell. The job-site is full of construction personnel and architects involved in the restoration of the interior and exterior of the building. Once they heard of the first aircraft's impact on Tower I, they all rushed up to the roof in time to see the second aircraft impact Tower II. They then stayed on the roof watching the resultant fires, the trapped people in the windows and ultimately the collapse of the two buildings. The common thought was, what would happen next. One man commented to me that watching it all unfold, it took on a surreal quality and his mind could not accept the reality of what he was witnessing. It wasn't until much later that day could he begin to realize the enormity of what had happened less than a mile from him.

Surprisingly, the general contractor at the Court House provided me with a site security pass and a hard hat. After showing some picture ID, I was allowed to walk through the security checkpoints and down the last few blocks to the Church Street boarder of "Ground Zero".

Dust and smoke from the fire, still burning deep in the ruble, was in the air and most of the workers and authorities wore protective half facemasks with filters. The smell was less than I expected and was the smell of a fire site with a strong burnt electrical odor. There was also a medium odor characteristic of an incinerator plant. The total devastation was awesome. One hears it so often but I have to reiterate again that television does not begin the do justice to the enormity of the damaged area. To totally appreciate what you are observing one has to have been there before and understand the size of what was the WTC complex. Tower I and Tower II are in the center with all 110 floors per building collapsed to ground level and compressed into the lower level and garage areas. Only an eerie section of each building's aluminum facade is still standing. Most of Building VII has also collapsed to ground level and there is only a section remaining of Building V. There are buildings or sections of buildings that are still standing but have received such violent damage that they look as though they are going to fall at any time. Surrounding the collapsed buildings are the buildings that have sustained collateral damage. The damage on these contiguous buildings ranges from minor to extensive. The copings, ledges and sills of these boarder buildings were still filled with paper and other debris. Even the luxury apartments across West Side Highway by the river have had about a third of their windows blown out. Nets have been strung over the facades of some buildings to prevent falling debris from injuring the site workmen who include police officers, medical personnel, firemen and construction personnel. The site now looks like an amphitheater with "Ground Zero" in the center and the large, badly damaged buildings providing the boarder.

All of the personnel at the site look tired. The police officers look like they have paid the price of little sleep and a lot of raw emotion. Their faces look like the faces you see of solders in combat photos. As tired as they were, you could tell by the way they held themselves that they were damn proud to be New York City police officers. There is a food tent sent up and there are areas for the workers to rest. Heavy construction equipment is everywhere collecting, loading and removing debris. Black Hawk helicopters cruise the Hudson River. The site resembled a military operation just after a battle.

For me, it was the type of scene that would take some time to absorb and quantify. I was prepared for and was conscience of the devastation and what had caused it and I was very much aware that I was standing at the edge of a site where upwards to 6000 people lay entombed. But, for whatever reason, like the men on the roof of the Tweed Court House, I was not able to feel the total impact of what I had observed until much later that day when I was back home.

I badly wanted to see the site and I am glad that I did. I think every American should see the area and understand what has been done to us. I know that it is both impractical and probably inappropriate to herd people down there, so those of us who have been to the site should try to talk about it and make everyone understand the enormity of the tragedy.

Thomas H. Rudder


Thoughts For Observing Environmental Common Sense

I would like to again address chemical cleaning in our environmentally conscious society. I have always maintained that high-pressure water and chemical cleaning performed by conscientious, professional contractors using proprietary products can be safely accomplished. Each contractor should obtain a copy and understand the rules set forth by his State's environmental protection agency. There will be a section addressing pressure washing and specifically as it is applied to building cleaning and the maintenance of the "run off" effluent.

Different States will have different rules, but in general, most States have some common guidelines. Although I have used the Connecticut rules as a template, the items listed below are generally universal and include...

1) There will generally be a published list of chemicals or biological additives which cannot, under any circumstances, be discharged. Most of the organic solvents are included in this list.
2) The discharge of power washing wastewater used for chemical stripping of paint, other than graffiti, will usually be prohibited.
3) The discharge of power washing wastewater into a storm sewer or to a surface water body will usually be prohibited.
4) If you discharge to an unpaved area, the area must be large enough to absorb the waste water into the soil without impacting storm sewers, surface water bodies or drinking water wells. Additionally, the pH of the wastewater shall be not less than 5.0 or more than 10.0.
5) Most areas will allow a discharge into a sanitary sewer as long as there are no paints or organic solvents. Once again, the pH range of the effluent must not be less than 5.0 or more than 10.0 when it goes into the sewer.

While engaged in any form of building cleaning, we recommend that all adjacent storm sewers be protected from any wastewater effluent. We also recommend that if a building is being washed with an acidic product and the initial runoff effluent has a pH of less than 5.0, the contractor establish a berm using soda ash in the path of the runoff. As the run off water flows through the berm, the soda ash will raise the pH of the wastewater to the desired range. Conversely, if an alkaline product is being used to clean the building and the initial pH is too high, then a berm of citric acid should be established which would serve to lower the pH into the desired range. Both soda ash and citric acid are safe, inexpensive products and are easily obtainable. Along with pH paper testing strips, they should be on every jobsite.

Regulatory agencies are looking to contractors to use good judgment in managing their wastewater effluent. My experience is that they are also willing to work with contractor/architect/owner teams to determine the best procedure to handle discharges on any given project. If we all work to regulate ourselves, we may be spared having unrealistic prohibitive, regulations imposed on us in the future.



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Hydrochemical Techniques, Inc.
PO Box 2078
Hartford, CT 06145

Tel: 800-278-7681 860-527-6350
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