For Professional Use Only
Safe for Glass and Anodized Aluminum
Myths and Facts Concerning Strong Acids on Limestone
There are some common misconceptions concerning the use of strong acids (such as hydrochloric acid) on limestone. The Indiana Limestone Institute literature states:
“Special consideration and protection shall be provided when brickwork is cleaned above the limestone. Strong acid compounds used for cleaning brick will burn and discolor limestone. Use of sandblasting, wire brushes or acids will be permitted under special circumstances, approved by an architect.”
The common misconception is that if a product is acidic in nature (with a pH less than 2.5), it should automatically be banned for use on limestone. because it would fall under the classification of strong acid and would do the type of damage indicated in the statement issued by the Indiana Limestone Institute. This statement would be true if using strong acids in their raw non-reacted state. Our modern limestone cleaners (OneRestore® and NMD 80) have been formulated and blended to successfully incorporate strong acids coupled with surfactant packages that clean without adverse effects on limestone. Throughout the country, OneRestore® has been successfully used to clean historic limestone as well as buildings that have limestone on their windowsills or as one of their components. Our new masonry detergent, NMD 80, which contains a greater amount of the buffered strong acid than OneRestore®, has been used to clean new and historic buildings that are made up completely of limestone and those that contain limestone as one of their components. Repeated inspections of these cleaned structures have been done over more than a four year period and have shown no apparent etch or discoloration has occurred. This etch and discoloration would have occurred and been grossly visible if the limestone had been cleaned with raw HCL or a similar “strong acid” type product.
OneRestore® and NMD 80 do not cause discoloration or etch on limestone. EaCo Chem provides blended products that contain a mixture of acids and surfactants without the adverse effects that are typical of products, which use raw acids as their main component or in an unblended state. Acid is just one of the many components in OneRestore® and NMD 80 and is why we feel it is appropriate to evaluate them on performance and safety issues, rather than on what on of the raw materials could do because in their finished state, the problems associated with low pH products do not exist.