The top photograph below of the Dorothy Eleanor Provoznik gravestone, that is 95 years old this year, at the Calvary Cemetery in Lorain, Ohio was taken on May 28, 2007 after it was cleaned with only plain water.
As can be seen, there was a white streak across the front side of the gravestone most likely made by a weed whacker that remained even after cleaning with a soft bristle brush. This stone is quite porous. It is almost like a concrete block.
The second photograph below was taken May 9, 2015 not long after water and D/2 Biological Solution was applied to it. The stone was scrubbed with a soft bristle plastic brush.
It was so amazing to watch as brown and green ‘gunky’ liquid just “oozed out” of the gravestone and came to the top surface rather quickly.
It is important to note that there are steel mills in the area and much pollution is in the air, unfortunately.
The gravestone was rinsed down well with water afterward. In a few minutes the stone began to dry and it looked as seen now.
This stone will be checked again this summer to see how it is doing!