Brick restoration has four main types of cleaning situations, they are:
- Porous Brick
- Glazed Brick
- Dry Pressed Brick
- Vertical Score Brick
The products used in our brick restoration process include:
OneRestore® - OneRestore® removes virtually all of the most stubborn stains that can occur on brick including the deepest pollution stains (vanadium, manganese, rust, etc.) without using harsh chemicals. OneRestore® has a mild odor and is safe for use on many surfaces (including glass and anodized aluminum) and around people.
Heritage Restorer- Heritage Restorer is a restoration detergent for historical or sensitive substrates. The product is based on our thoroughly developed non-corrosive technology. Cleaning power is achieved by a combination of over 25% surfactants, mild acids to melt metal and mineral oxide residue and water based solvents for hydrocarbon based residues.
GS Restoration - GS Restoration is our ammonium bifluoride product. It has been used for years in some seriously tough situations. GSR was designed to be the safe alternative to heavy duty acids. While it is not recommended for use on glass, many buildings have been cleaned without covering the windows. Extreme caution should be taken to protect surrounding surfaces.
Stripper Cream - Stripper Cream is the recommended product to remove thick, external black crust from limestone and masonry as well as graffiti. Stripper Cream is also a thickened multi-layer paint remover. It is very slow to dry and can remain on a surface for days. While all of the bricks can be successfully cleaned using one of our restoration grade products, the technique used for cleaning may vary. Before going into the individual techniques, I would like to address a common situation. As water migrates through the masonry wall (due to roof leaks, bad capping or deteriorated mortar joints), it creates deposits we call black crust. The chemical make-up of the stain may vary with the substrate and environment; we consistently recommend Stripper Cream. It does not pay to try and hurry this removal process, as inadequate dwell time simply increases the number of times the process is repeated. If the temperature is above 68° F and Stripper Cream’s chemistry mixes optimally with that of the stain, an hour dwell time may be adequate. Scratch tests should always be performed before removing the caustic. If you scratch with a putty knife and do not see the substrate (the surface you are cleaning), leave the caustic on longer, mist the surface with water, or add more product. If you see no reaction at all, we recommend trying NMD 80 undiluted, sprayed on repeatedly, followed by a pressure wash rinse.
In the early 2000’s we introduced OneRestore®, which is a hydrochloric based detergent. The buffering in OneRestore® enables it to be safer for use than traditional methods and even more effective. While straight hydrofluoric acid presented challenges to adjacent substrates, OneRestore® virtually removes those challenges and presents further opportunity. We always recommend proper testing prior to full scale cleaning on brick or any other substrate to assure compatibility.
To start the cleaning process on porous brick, pre-wet the area to be cleaned. Work in sections that you can comfortably cover without allowing the product to dry. Always work in a repeatable pattern; the hallmark of quality restoration is evenness and consistence in appearance. Since OneRestore® and Heritage Restorer are spray on/rinse off products, you will be able to cover a much larger area than bucket and brushing. Start from the top down to achieve excellent results. Spray the OneRestore® and Heritage Restorer undiluted to a damp wall (the wall should not be saturated with water) and allow it to dwell for approximately five to ten minutes without letting the product dry. If testing shows multiple applications are needed, apply the next application wet on wet without rinsing in between.
After all the applications have been applied, thoroughly rinse with a pressure washer. I recommend a four gallon per minute unit at 2,000 PSI. We know bigger pressure washers and are quite common, but we also know you are looking for excellence and craftsmanship. A five gallon per minute at 3,000 PSI machine gives you 15,000 cleaning units of power at the nozzle. A four gallon per minute at 2,000 PSI machine gives you 8,000 cleaning units of power at the nozzle. The truth is that if you are using power to clean, you are water blasting, not cleaning. 36,000 PSI can cut through steel, but it cannot lift out a rust stain from brick! The right products do the cleaning without harming the surface and at an appreciably lower maintenance and labor cost. Using the right products and 8,000 cleaning units will be sufficient, cleaning with increased safety for the substrate, precision on the part of the user and equal results 99.5% of the time.
Glazed brick is smooth in appearance, due to the finish that uses the same raw materials that are in glass: silica, a flux and water. Fired to a high temperature, the brick has a dense finish that does not absorb water. This finish is even more similar to glass in that it can be burned by chemicals just as readily. In fact, the original purpose of GSR was to clean this type of brick without damaging the surface. Glazed brick is a situation where two mild applications are better than one very strong application. GSR is best used at a higher dilution with a double soak. Certain glazes have a tendency to absorb pollution or metallic stains. The stains tend to be black and occur most often under sills eaves on houses. They generally originate from air borne solids, clay or dirt. GSR is optimized for removing these stains without requiring glass to be covered. When using GSR, keep surrounding surfaces wet, especially those that overspray could potentially land on. One myth about chemicals is that “right out of the jug” is as strong it will ever get. This is not true. In fact, all liquids being applied as restoration detergents contain water. It doesn’t matter how much water they contain, eventually the water will evaporate. As it evaporates, it leaves the chemical solids reacting on the surface at a higher concentration (stronger than “out of the jug”). This is when burning occurs. The key is not allowing the chemicals to dry. While GS Restoration was developed for this exact type of brick, over the years we have found that OneRestore® and Heritage Restorer are the best overall products for this or any type of restoration work. There will always be a place for GSR; however, more cautions are necessary when using the product.
OneRestore® and Heritage Restorer have more versatility and safety. Much like on porous brick, OneRestore® and Heritage Restorer are capable of removing some of the toughest stains possible. OneRestore® and Heritage Restorer have a few simple rules of use:
- Do not allow it to dry on glass or anodized aluminum.
- Do not use on self-cleaning glass or glass with a metallic oxide finish on the number #1 surface facing the outside.
- Be sure to test properly to make sure it is compatible with all components of the building.
The application process will be the same for porous brick. Pre-wetting is not necessary unless it is used to flash cool the surface. Since glazed brick is not porous, the water will run right down the wall.
Dry Pressed Brick
Dry pressed brick is one of two types of brick that have been problematic to clean in the past. Results may vary on this type of brick, depending on what methods were used in the past to restore them. Dry pressed brick has a smooth finish but is very porous, which allows quick absorption. Prior to the development of OneRestore®, the only real way to clean this type of brick was with a heavy acid (hydrofluoric) which was needed to penetrate deep enough to lift out stains. The problem is that hydrofluoric acid will burn the surface and set the stains simultaneously. The techniques suggested used to include a two step process with GSR then LCS. While the results were acceptable, we could never claim excellence.
With the development of OneRestore® and Heritage Restorer the ability to achieve excellent results has dramatically increased. There is far less of a chance to damage the surface. Care should still be taken not to allow the products to dry; testing is still recommended. As with porous brick, pre-wetting the surface will benefit the cleaning process. Saturating the wall with water is never recommended.
Vertical Score Brick
Vertical Score Brick has traditionally been more difficult to clean due to its grooves. When asked to clean the type of brick with vertical scratches across the face, always demonstrate and make sure the customer knows what they will be getting. Since OneRestore® and Heritage Restorer are so versatile, the results will still be better than with other products of the past. Testing is the key to how much product is to be used and what technique will give the best results. Since vertical score brick are not very porous, there is very little benefit to pre-wetting (with the exception of flash cooling).