There are three things I have to do when called in to a stain job. First I need to identify exactly what the stains are and where they came from. Second it is necessary to figure out the best and most simple and safe way to remove them. Third I have to figure out the best way to prevent the stain from coming back. If it does come back then this has to be dramatically minimized to the point where it can be removed again with great ease.
There was a building in Worchester Mass that I was called into several years ago that had some rather unsightly stains. It was a multistory building at least ten stories high. About a third of it had a shiny metal fascade and the remaining two thirds was glass. If I told you the name of the building you would know it. The property management company called me in with no clue about the damage. They didn't have any answers. But needed these so they could deal with the problem. I arrived about ten minutes early to the site. Within five minutes I had all the answers! It was way too easy.
The building was in the middle of Worchester which is a rather large city. So the rain there is quite acidic. The exterior of the building was concrete. It had not been properly sealed with a quality sealant to prevent the breakup and leaching of the minerals from the inside of the pores. Which was exacerbated by the acid rain. Carried out from the pores by the rain and over the glass, the minerals were deposited on the glass when the sun came out to dry the water drops. As water drops dry the mineral content of the drops is raised to a pH of about 9. This then causes the water to etch the glass. So that the minerals that are left behind lock on to the glass, and are impossible to remove with even 0000 steel wool. Most of the time. What made this worse was the fact that there were no drip edges installed over each window to divert the rain water. The man who called me in couldn't figure out why some of the windows had no stain at all. The answer was simple. The shiny metal fascade was directly over those windows which were stain free. The metal protected them.
Next I needed to explain and demonstrate the most simple but safe way to remove the stains. What I mean by safe is no bad acids that would etch and no bad abrasives that would scratch. I was able to determine that the windows had a solar control factory applied metal coating on the first surface. It was an easy coating to see through. So difficult to notice. But it was still there. On the weather side of the IGUs. Metal coatings are the easiest surface to clear of water stains. Clear glass is more difficult. Then dark glass is the most difficult. Also anytime glass has been in contact with hydrofluoric acid or has been polished with a superabrasive such as cerium oxide, it becomes much more difficult to clear of second or third generation hard water stains. After giving it a go with paper towels and a cerium oxide superabrasive the stain came right off. So the owners of the building were looking at a one step "fairly quick" cerium polish. I make my own compounds based on different superabrasive blends.
The final answer to this problem was how to keep the stains from coming back again. First it is necessary to seal the concrete properly with one of the best hydrophobic sealants possible. It is easy to test a building to see how resistant it is to leaching. Just throw water on it. The water should bead up and roll off. Studies have been done on multiple products based on a wide range of chemistries. The next step should be to seal the windows with a hydrophobe. If you are sealing glass the choice is simple. But if you are on a titanium or a tin coating not so much. Although it still must be done! The next part of the solution would be to somehow build into the building drip edges directly over each window not below any shiny metal. When the architects design these buildings they make sure that the exterior of the building is flush with the glass. This is to maximize the number of square feet that will be rented. They also will put the bleed holes for the rain right over the windows. You see nobody understands that glass can be etched and stained by water. This is actually a type of water damage that no one even talks about.
So there you have it. All three parts. What is lacking in this post are many details. Such as and especially names of certain products that are used to remove the stains and protect the concrete and windows from damage. For that you have to call me. Then we can look at your building together and set up some time experiments to come up with the answers that will work best for your building and your problem.
Written by Henry Grover Jr.
603 498 9474
No comments:
Post a Comment