Historical buildings are a lot more important than people realize. They are physical places that give us a peek back into important or significant cultural moments in our history. That’s why you need to know everything you can about restoring them if you or your company has been contracted to do so. It might seem like a simple job at first, but there are many considerations that fly under the radar when it comes to restoring historical buildings.
In order to bring you up to speed so that you and your company can do the best job possible when attempting to restore a historical building, let’s go over three important things you need to keep in mind when tackling such a project.
1. Carbon Staining in restoring Historical Buildings is a Real Problem
One of the main problems that many historic buildings face is dealing with carbon staining. Carbon staining is when the outside of a building becomes stained with a black, soot-like substance. This can happen if a building is close to a high-traffic roadway or is exposed to the burning of fossil fuels like oil, gas, or coal on a regular basis.
These air pollutants will leave a water-resistant, sticky film over the exterior layer of a substrate. Once there, this sticky film will trap more airborne pollutants, creating an amalgam of unsavory material all over the face of the building. For historical buildings, this often means an ugly, black stain that can’t be cleaned off with a simple water wash.
Polluted acid rain actually will wash this sooty film off, but unevenly. This results in very pronounced streaks of black pollution on the outside of the historical building.
2. Sandblasting Historical Buildings is Never OK
There has been a recent trend in the maintenance and restoration of historical buildings which involves sandblasting for the purpose of cleaning. Abrasive grit-blasting is the act of using a power-sander to essentially scrape away any soot or unsightly material on a building that is impossible to wash off with water.
Not only is this practice inefficient, it’s harmful and lays the groundwork for further degradation of the building. One of your goals as a commercial business hired to restore a historical building should be to accomplish the goal without compromising the building in any way, but sandblasting does just that.
Sandblasting not only blasts away whatever material you’re trying to scrape off of a substrate, it physically harms the substrate itself. This is because sandblasters are typically so powerful that they actually expand the surface area of the substrate, thereby exposing malleable stone to even more dust and erosion.
This actually creates the perfect environment for biological organisms to multiply in moist, dark surface crevices. As a result, a stain can actually be driven further into the substrate and become more prominent with a higher level of water retention.
3. Alkaline Cleaners Makes a Great Solution
If you want to remove carbon stains from your client’s building, you need a specialized product which won’t harm the substrate such as alkaline cleaners.
Alkaline cleaner prewash is made from an alkaline gel which is non-acidic and very effective at dissolving the heavy carbon crusts. It’s able to be used in precise applications such as spot-cleaning, giving it one of many advantages over sandblasters. When properly applied, the prewash will dissolve and aid in the removal of heavy encrustations of carbon from limestone, brick, sandstone, and terra cotta.
Once this is complete, the masonry will need to be neutralized with the afterwash. This will ensure that all residue from the prewash is removed, allowing the masonry of the historical building to retain its natural appearance and color. The afterwash is a mild, acid-cleaning compound which is organic and will not harm masonry in any way. It works great in humid environments as well, making it the perfect product for historical preservation in just about any climate.
Because the afterwash is completely organic and non-harmful, it is also helpful for buildings that have already been damaged by sandblasting. The prewash is able to be diluted and used with a dwell time of anywhere from 30 minutes to two hours. This gives workers some flexibility when it comes to dealing with historical buildings with substrate integrity issues, such as those that may have dealt with sandblasting before.