CATEGORIES: BRICK - SANDSTONE - VENEER

BRICK RESTORATION

Brick restoration has four main types of cleaning situations, they are:

• Porous brick
• Glazed brick
• Dry pressed brick
• Wire or water cut (scratched face) brick
  

Porous Brick Restoration
This job is traditionally done with hydroflouric Acid while the cleaning is generally quick and effective it is also always dangerous and requires both constant attention to safety and protecting virtually everything around. HD Acid has been our most powerful tool in this type of restoration for forty years. Beginning in the 1970’s though we started to work on a much safer alternative, the GS Restoration. This started principally as a more effective alternative to HD Acid for glazed brick, which would often burn before it cleaned. Now after years of refinement and with the addition of detergent chemistry perfected for the ultrasafe SafeRestore formula we recommend starting the testing process with GS Restoration and using HD Acid only as a last resort. The difference in cost includes: not covering the glass, greatly reduced danger to humans, and much lower chance of burning the surface.

Start by prewetting the area to be cleaned. The most common application method with HD Acid is bucket and long handled tampico brush. Especially with HD Acid the importance of safety gear cannot be stressed enough. The brush should always be kept below the waist, if possible because of splashing drops. You do not want the acid to dry so work it in a rather small area. Five by five is usually good. Always work in a repeatable pattern, the hallmark of quality restoration is evenness and consistency of appearance and doing as little harm as possible. Generally, we recommend, in brick restoration starting at the bottom and going up. This keeps the surface below clean and wet and less likely to stain. But you can just as easily work from the top down and get excellent results. All good acid restoration is a double application process, many do not even realize they are rebrushing as they apply the chemical but it is almost always occurring. The alternative to this is a single strong application. HD Acid is capable of cleaning successfully like this but your concentrations will be stronger and liability higher and the danger of damage increased. Consider working with a greater dilution but applying it twice. This is often a more effective means of restoring; it keeps the surface wet longer, increases dwell time, and generally allows better release of deep stains. After application thoroughly rinse with a pressure washer. I recommend a 4-gallon / minute at 2000 PSI, as this is very easily controlled combination to work with all day long.
We have used much bigger pressure washers and know that they are quite common but we are talking about excellence and craftsmanship. Five gallons/minute at three thousand PSI gives you 15000 cleaning units of power at the nozzle. Four gallon / minute at 2000 PSI gives you 8000 cleaning units at the nozzle. The truth is if you are using power to clean, you are water blasting not cleaning. 36000 PSI can cut steel but it cannot lift out a rust stain. The right chemistry does the cleaning without harming the surface and at much lower cost appreciably lower maintenance and labor cost. The right chemistry and 8000 cleaning units will be sufficient and give equal results 99.5% of the time.

GLAZED BRICK
Glazed Brick is smooth in appearance. It has a finish that uses the same raw materials that are in glass; silica, a flux and water. Fired to a high temperature it will have a dense finish that does not absorb water. This finish is like glass and can burn just as readily. That is the original purpose of GSR; clean this type of brick without damage to the surface. GSR is not totally safe on glass. Though thousands of buildings have been cleaned without covering the glass. This situation again is one in which two mild applications are better than one very strong one. Certain glazes have a tendency to absorb metallic or pollution stains. These Stains tend to be black and occur most often under sills. On houses there may be stains under the eaves. These are generally from air borne solids, clay or dirt. GSR is optimized to remove these stains without covering or damaging glass or glaze. There is not much benefit in prewetting a glazed surface because they are not very porous. If you are spraying on GSR, which because of its’ safety is quite common, you should pay attention to keeping wet any areas where over spray may land. One misunderstood aspect of the chemistry by the cleaners is that right out of the jug it is as strong as it will ever get. That is not true. All liquids being applied as restoration detergents contain water. However much water they contain, water does and will evaporate. As it evaporates it leaves the chemical solids reacting on the surface at a higher concentration (stronger than right out of the jug). This is when burn occurs. GSR used properly will not harm glass or plants and is very safe to the applicator. The essential caution with this product is that you cannot allow this evaporation concentration to occur. Wetting and rinsing maintain dilutions which makes the product non-damaging. Allow the product in high concentration only those stains that you need to solubilize and rinse away. Top to bottom or bottom to top does not matter here, controlling over spray and rinsing and double soaping is what will make an excellent job on glazed brick restoration. Double soaping is applying the chemical twice to the same area. You do not rinse in between and you do not allow it to dry. Different stains will require different dilutions or even uncut product to be used; you must always test. After a thorough soap application rinse with a pressure washer to remove all the softened soils. Generally one cleaning process will be enough if your dilutions are correct, but if not resist the temptation to go stronger, just repeat and increase the soak time. A stain that has not come all the way out but is mostly gone is deeper because it has soaked into the brick. Your first cleaning process will have created a wet area in this porous portion of the brick and so it will stay wet longer. Reapplying the soap in this area while you clean somewhere else, keeping it wet on the surface, and then slow rinsing with high pressure again is the best way to pull out a deep stain.

DRY PRESSED BRICK
This is the first of two types of brick that are problematic at best. There are solutions that have been successful but many situations will provide you with no chance of success because of previous damage done in prior cleaning attempts. Dry pressed brick has a smooth appearance but is very porous. If you spray water on a dry press and stop you will see some surface run but ultimately a tremendous amount of absorption will occur. This is the reason this brick is difficult to clean. Brick this porous will normally require HD ACID with hydrofluoric to penetrate deep enough to lift out these stains. The problem is the hydrofluoric acid will burn the surface and appear to set the stains simultaneously. The technique we recommend that has had the most success, though I will not claim excellent results, is an application of the LCS diluted between straight and 4 water 1 soap on a prewet surface followed without rinsing by an application of GSR cut 1 to 1. This seems to loosen the deep staining without creating the burn on the surface. The LCS can strip paint so be careful around any non-masonry surfaces. It is also possible to try a very dilute HD Acid at between 7:1 to 20:1 with a double soap application on a prewet surface but always test in an inconspicuous area first.

CUT FACE BRICK
This brick usually just does not clean very well. If asked to clean this type of brick with the vertical scratches across the face always do a demonstration and make sure the customer knows what they will get. It is a very simple process to clean this with HD Acid at an appropriate dilution determined by testing, It is not porous so prewetting creates limited benefit and does not burn very readily so start at 2:1 or 3:1 and work up to double soap 7:1 to 10:1.