WHERE DO STONE STAINS COME FROM?This is a common question for property owners, managers, contractors and suppliers all over the world. Many factors can cause stone stains. Most stains are due to insufficient maintenance, inappropriate water-repellants used to seal precast, caulking leaching onto adjacent stone materials, and careless window cleaning practices.If the precast on your building was sealed but is still leaching minerals onto glass surfaces, click here. DIFFERENT TYPES OF STONEThere are many different types of architectural stone material, all of which have different characteristics which need to be understood before determining the best means of maintenance or restoration.It is important to select a product that will allow you to achieve the desired results when cleaning stone materials. Each of Presto’s products has a suitability chart, within its product data sheet, that shows the differences in stone types, and their compatibility with the individual product. Presto’s Five Stone Classifications:
PRESSURE WASHING STONEFor years people have believed that more pressure was better for cleaning stone. Each time a stone surface is washed using high pressure, a layer of the stone material is removed. This is especially detrimental to precast and concrete materials that have a thin top layer on the material that covers the coarse aggregate within the stone. In many cases, using lower pressure in combination with the proper products will safely and effectively clean the stone without altering the surface of the material. View Before & After Photos COMMON STONE TREATMENT APPLICATION MISTAKESMany times damage is caused by incorrectly choosing or incorrectly using a product. Products should always be utilized in the manner outlined on the label, and in the product data sheet.When you are cleaning stone, damage is normally caused in the last few applications of the chemical, especially when trying to get the material just a little bit cleaner. Sometimes stains are so deeply imbedded into the material, that they can never be 100% removed. Knowing when to stop applying a product can save the stone from damage. It is important to realize that when using an acidic product, like Presto’s Stone Restore® HD, a very thin layer of the stone material is dissolved in order to remove stains that have permanently adhered to the stone material. Each application of this product will dissolve another layer of the stone as well as the stain that is imbedded into it. Many times adjacent surfaces are damaged due to performing restoration or cleaning services without preventing over spray from residing on unintended areas. It is very important to protect adjacent building surfaces, or include the restoration of adjacent surfaces when using chemical processes. Overspray is a common occurrence during the application of stone sealer. Many sealers are very difficult to remove from surrounding metal and glass surfaces, often despite “glass friendly” claims made by the manufacturer. Products are often determined to be "glass friendly" when tested in a laboratory environment; since it is easily removed after application to perfectly clean glass, or removed without first baking in the sun. In real-world application, after washing a building’s stone, there is stone sediment on the glass and frames. The stone sealer overspray reacts with the sediment forming a sticky, oily residue that is baked on by the sun, and becomes difficult to remove. In this situation, Presto’s EnviRestore® products will often effectively remove these stains from glass, metal and polished stone surfaces, without damaging the substrate. CHOOSING THE RIGHT STONE CLEANING PRODUCTSImagine taking a shower and not using soap, or washing the dishes with oil instead of dishwashing detergent! This may alarm you as much as it does us when we see contractors using mediocre or incorrect products to perform building maintenance services. For example, many times pressure washing is performed on concrete without using chemical cleaners, and without the application of a sealer after the pressure washing is finished.Properly selected cleaners loosen many different types of soils that adhere to concrete similar to the way dishwashing detergent carries oil away from dirty pots and pans. De-greasers help to loosen oils and grease, bleaching agents work to remove mold and algae, acids work to remove stains such as rust and efflorescence. In conclusion, choosing the right product is essential to the overall outcome of the project. It’s important to choose the most suitable product for: 1) The stone material to be cleaned, and 2) The stain that is to be removed. Many times the wrong product is selected due to the consideration of only one of these factors, and the desired results are not achieved. Presto has developed a product to tackle every stain commonly found on stone surfaces. Below are links to our suitability charts for cleaning many different types of stone materials and stains. These charts will guide you to the product best-suited for your specific cleaning need.
When the correct products are used, stone is restored to a state similar to that of its original manufactured condition. When a test area is performed with our products versus our competitors’ products, it is visibly clear that Presto's products provide the most impressive results on the market.
REASONS TO SEAL STONE SURFACES AFTER CLEANINGSealers should be used after the stone cleaning process to close up the pores of the concrete or stone, in order to prevent the penetration of water and oil which act together to stain the stone again. Sealers will help keep stone cleaner for longer and help to protect from water damage, therefore, prolonging the life of the material.When restoring stone, it is always important to identify the cause of the stain, and prevent the stain from reoccurring at the source. After restoration, and curtailing the source of staining (if possible), it is important to protect the surface in order to help prevent future restoration.
SELECTING THE RIGHT STONE PROTECTIONThere are many different types of water repellant materials available today. Silanes, siloxanes, silicones, acrylics, waxes, epoxies, siliconates and fluoropolymers; just to name a few. In addition, many of these materials can be mixed together to create a totally new material for use on various surfaces. It is important to not only chose the correct product for the required application, but to also ensure that the product is applied properly. Presto is the first company in the world to create an exclusive line of products to specifically combat the problems involved with precast leaching onto, and staining, adjacent glass surfaces. Below are links to our suitability charts for cleaning and sealing many different types of stone materials. These charts will guide you to the product best-suited for your specific stone restoration or stone sealant need.
STONE SUITABILITY CHARTS
#1 MISUSED STONE SEALER: 40% SILANESilane is an oily liquid that is designed to react with the silica in stone. Upon application, silane forms a resinous gel that fills in the cracks and crevices in the stone, blocking water from penetrating into the stone. Over time this resinous gel hydrates, and creates a harder, glass-like material that becomes part of the stone itself.Silane is one of the smallest of all water-repellant molecules, enabling it to penetrate deep within the substrate, and protect structural materials. While silane water repellants are suitable for many situations, they are undesirable for use on high-rise buildings with flush mount window systems because this material can actually help to create unsightly stains. It’s important to select a company that creates products with all of your building surfaces in mind. The water repellant most commonly used today to seal architectural stone consists of 40% solid content silane. We have seen countless buildings that have sealed their precast using 40% silane only to have the material break down and produce excessive leaching in as few as two years from the date of the application. In our experience 40% silane is one of the least effective product options available for vertical precast surfaces, especially when flush-mounted windows are present. It’s also important to understand the disadvantages behind using silane so that you will have all the information that you need in order to make the smartest decision possible when selecting a sealer for your building’s stone surfaces:
Silane is hardly a “Green” solution to building maintenance!Silicone and other new fluoropolymer materials, react with moisture in the air, and harden without requiring contact with silica. These more suitable materials will evenly cover the surface of the stone, and cure in place, remaining on the surface, and protecting it for up to 20 years. These products are extremely UV-resistant, and repel water as well as many types of environmental staining, including oil. These materials are approved for spray applications, and it is easy to see why they are considered to be the “greenest” option available today.RESTORE, PROTECT AND MAINTAINIt is critical to select the right combination of products to protect the environment, and maintain the exterior beauty of your building. Presto has designed products to work synergistically – not against one another.Follow Presto’s three-step process: Restore, Protect and Maintain.
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