There is an apparent controversy between preservation societies and the paint and chemical industries. Such societies have found that traditional [organic] paints and protection coatings provided by American industry do not provide the protection and longevity that they are looking for in the restoration and preservation of historic structures. Further, such products actually increase the rate of deterioration!
The industry denies this, pointing to their products and showing ASTM and in-house tests to prove they are right. They will tell you about the move to zero Volatile Organic Compounds (VOCs) making organic paints safe. They forget to tell you that the colorants used give off VOCs making their zero claims misleading and mischievous. If the product is organic, it is hazardous to one's health and safety and to the environment, whether it has VOCs or no VOCs.
These two groups are reaching an impasse, and as the preservationists have limited clout they will be ignored as the industry closes ranks on this issue. After this "storm in a teacup" is laid to rest by the industry, the preservationist still has the problem. Because many societies cannot think outside of the box, they will toil and fret and continue their good work buying the latest products from the industry, products that continue to fail and increase the cycle of deterioration.
We find the topic of coatings for restoration very timely as our company is promoting the use of an alternative technology inorganic in nature that can provide the necessary protection and extreme durability with little or no impact on the environment at about the same initial cost as organic paints and coatings.
Short Course in Chemistry
Chemically, the problems that are created by the short life traditional organic paints can be virtually eliminated by simply moving to inorganic paint and protection coatings. Logistically, one must turn to Europe, as North America has no inorganic paint manufacturers of note.
The three major silicate paint manufacturers in the world, which have primarily focused on the restoration and preservation market, do supply the North American market through exclusive distributors. The major inorganic paint players in the restoration business worldwide are Keim and Silin of Germany and Silacote [known in Europe as Hansa Silicat] made in Latvia. Due to a recent breakthrough in the tinting process the Silacote line is now also available to the consumer in North America.
Inorganic paint coatings are made of natural compounds from the earth strata, such as quartz, minerals and inorganic mineral colorants, bound together with a potassium silicate binder. Silicate paints are basically colored liquid rock, fully compatible with other inorganic substrate materials.
When applied to inorganic substrates such as concrete, cement plaster, lime plaster, marble, natural stone, and other similar material, the silicate coating bonds to the substrate chemically forming an insoluble compound of paint and substrate. This chemical bonding ensures that the colored coating will not peel, chip or flake off as would happen with traditional organic paints.
Organic paints rely on mechanical adhesion they are not compatible with inorganic substrates, or virtually any other for that matter. Organic paints are basically an oil derived liquid that, when dry, forms a film that sits upon the substrate. As an oil bi-product it is already in a state of break down, or decay, from its carbon chain origins and this is accelerated when attacked by ultraviolet light, the climate, pollution and other hostile aspects of the environment in which it is used.
Take a Deep Breath
The most serious defect in this technology is that the organic paint film does not breathe. When applied to an inorganic substrate, such as concrete, the heat buildup by the film draws moisture from the substrate to the underside of the adhered film. This moisture brings with it calcium and other alkali salts that build up between the paint film and the substrate. This is known as efflorescence, a white powdery substance.
The paint film begins to delaminate from the substrate, being pushed off by the accumulating efflorescence and water. On other porous substrates, such as clay-based brick, a similar delaminating takes place primarily due to the moisture buildup in the grouting, which once again brings the alkali salts to the surface pushing off the paint. Very porous bricks will attract moisture and this moisture, when heated, will create delaminating. Moisture continues to be drawn up during the heat of the day and eventually "water bags" appear which burst due to this cycling of heat buildup.
The heat buildup of the organic paint film can also cause significant substrate cracking, plaster delamination and cracking of the joints in brick façades. When moisture is allowed in from the film failure, it can penetrate into the building, especially under high wind conditions. This increased moisture penetration accelerates the film delaminating process.
During this continuing cycle of deterioration ultraviolet (UV) is taking its toll by drying out the synthetic organic film coating and making it brittle. In addition, it is making the color fade and chalk badly. The life of the coating is therefore short and the underlying substrate is most likely cracked.
The efflorescence brought to the surface is extremely difficult to neutralize in order to reapply the next coating. The repeated cycles of painting, stripping and repainting will increase in frequency as this high alkali buildup on the surface and in the subsurface dominates to the point that re-plastering is eventually required as the organic paints just will not adhere properly for long-term service.
The moisture that got through the film barrier is now in the substrate and is moving to the inside of the wall where another organic film forms a non-breathable barrier. Here again the efflorescence formed on inorganic substrates will push off the interior paint and one has the efflorescence problem on the inside.
The common factor here is the coatings' inability to breathe and pass moisture. Another factor is the damage by UV that attacks the film polymers, drying them out and making them brittle. In such a condition they are unable to take the constant movement of inorganic substrates through humidity changes and other natural thermal, climatic and physical stresses. When these organic coatings fail, the substrate will require a full removal, repairs to the cracked substrate, and some neutralization of the efflorescence areas.
In the business of restoration, with limited budgets and limited manpower, the continuing cycles of escalating deterioration and increasing costs, are serious problems that will not go away soon.
Inorganic Bond by Nature
In comparison, inorganic mineral silicate paints form a compound of paint and substrate. On inorganic substrates, the coatings are chemically attached using calcium and other alkali salts plus carbon dioxide. Most silicate paints/coatings have a high vapor permeability rate in excess of 90 percent in other words they breathe quite well, moving the moisture through the substrate, keeping the substrate dry. No efflorescence takes place as there is no moisture buildup and the coating itself has used up much of the alkali salts to form its chemical bonding process. Such a chemical compound will not peel, crack or chip off the wall. The durability and protection needed for several decades can be achieved by a one-time application of inorganic paint.
Quality manufacturers of inorganic decorative coatings use inorganic colorants which are not affected by UV they are light-fast and continue to be inert, providing an extended life cycle many times more than organic coatings. Coated buildings are expected to not require re-coating for decades, and even then a single coat, over a pressure washed existing silicate paint application, is all that is generally required for several more decades of life.
Although there are few structures in the U.S. using silicate technology, one particular structure that is using it is the Sheraton Hotel in downtown St. Louis. It was coated some 20 years ago and it still looks good. This building was restored and the silicate coatings were used on the exterior at that time. In Europe, several buildings are over 100 years old, fully protected and still going strong!
What is good for the preservationist is also good for the consumer. One must smile at the hours of deliberation by preservationists, designers and consumers alike, in getting just the right color for their organic coating from the paint supplier. Depending upon the grade of the paint, this color begins to fade from day one, especially if it is an exterior application. Within a few months, if you applied a strip of the original paint over the area previously coated, the difference is significant, particularly in certain color shades.
In comparison, the inorganic selection would not change for decades! Color selection for restored and preserved buildings must try and duplicate that which was used centuries ago. As the color coating made centuries ago, for the particular building, was inorganic, doesn't it make sense to restore it with an inorganic coating to provide authenticity!
Mold and Mildew
Toxic mold and fungi growth problems in North America continue to escalate. Mold and fungi forms when moisture is trapped and cannot dissipate. Organic coatings are one of the main causes of mold growth in all buildings, historical or newly built. The film itself allows moisture to form and run down to lower areas, such as cracks and crevasses, through gravity. Typical areas are the kitchen, bathroom and basements. High humidity and hot water from cooking and showering provides most of the heavy moisture that creates the perfect environment for the airborne mold spore to form and grow. If the moisture forms between walls and the mold gets a foothold, it will eat anything upon which it exists creating toxic gases that build up in the wall cavities and are making many people ill. This mold will also eat the timber supports, producing rot and reducing the structural integrity of the building.
The use of an inorganic coating eliminates much of this problem as the coating breathes and does not trap moisture. The coating itself is inert and of a high alkali content which will not support mold growth. Due to its high permeability factor, condensation does not take place and walls and ceilings are kept dry. Silicate paints are non-toxic, non-allergenic and non-static so they do not attract dust and dirt.
Whether one is restoring a building or building a new structure, the continued use of decorative organic coatings will perpetuate this toxic mold cycle of building deterioration and an unhealthy living environment created by unchecked moisture. Stop the moisture and you can stop the mold.
And then there is the safety aspect. Organic paints are combustible and can catch and spread fire readily from one area to the next, giving off clouds of highly toxic smoke that can asphyxiate a victim very quickly. This extra fire intensity and spread, and heavy toxic smoke, makes it very dangerous for rescuers and fire fighters. American frame houses, and even masonry structures with wood stud/gypsum interiors, leave little time for escape and the structure is generally completely consumed by the fire. Major old structures, mostly built out of stone, are still subject to quick flame spread, heavy toxic smoke and high heat when painted with organic products. Although more of the structure would be standing, due to its stone/masonry construction, the interior would most likely be destroyed.
On the other hand, inorganic coatings are non-combustible. They won't even burn. For example, our Silacote product has a Class A flame spread rating under ASTM E84 for concrete and plaster and for gypsum wall and ceiling applications with zero smoke development. They will not, therefore, contribute to any flame spread and will provide no smoke development.
If the walls and ceilings of a typical room were coated with an inorganic coating, the non-combustible structural substrate area would be over 70 percent. This significant reduction in available flame spread would be expected to slow the fire down and possibly keep it localized, giving more time for escape and less danger to the rescuers and firemen.
When one is restoring a historic structure, inorganic coatings would be expected to reduce the fire impact and give more time for escape. From an insurance point of view, we are sure that premiums could be reduced by negotiation when inorganic paints are used as the insurance risk is much less. This could provide savings for the preservationist to spend in other areas.
Those preservationists who have sought answers to their problems over the years are familiar with and use silicate-based coatings. Those who are not educated in this inorganic technology should step "outside the box" and discover how those in other parts of the world use such technologies to decorate and protect their historic structures. Only when Americans create a demand for new technologies in the paint and protection coatings industry, by seeking and using new technologies from overseas, will the North American industry make a change.
Preservationists must become educated on the vast fiscal, health and safety benefits of inorganic versus organic coatings. Once educated on the performances of each, there should be no doubt which technology will be chosen.
Our company is doing its part by making this technology available. Except for some members of the environmental (Green) movement and educated restoration groups, very few others are aware that they have a choice now. Even then, because the inorganic coating costs slightly more per gallon, there is great resistance.
Only through challenging articles in the media and support from environmentalists and others that care, can the people be educated in safe technologies so that they can make a choice. The choice is simple and clear: whether it is a waterproofing sealer or a decorative paint, the way to a more healthy and safe living environment is with inorganic coatings. To protect the environment and the manmade structures sitting therein, natural inorganic coatings and products should be the way forward into this new millennium.
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