Masonry Cleaning
The cleaning of historic masonry is one of the most important aspects of a restoration project. Simple cleaning can make the difference in the overall impression of a project, regardless of any structural or sub-surface issues that may have been sucessfully resolved. This review of masonry cleaning covers the most common means and methods, including both chemical and mechanical techniques, some old and well-known, and some newer methods that are less familiar.
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Water-Only Cleaning Various Cities, Various Counties, California Review of Water as the Sole Medium for Cleaning of Masonry Here, we are cleaning some brick at the Presidio in San Francisco using a garden hose. No chemicals, no pressure. In this case, it may have been the lesser of two evils, since the original mortar between the bricks was poorly washed beach sand and lime mortar. Any excessive water pressure would have blown away the original mortar. This was probably the optimum cleaning solution unless the owners were willing to remove and replace the outer 3/4" of all the original pointing mortar. From a strict Historic Preservation point of view, this would be less than optimum. |
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Chemical Cleaning Various Cities, Various Counties, California Review of Various Methods of Chemical Cleaning As with all cleaning methods, the type of stone or masonry and the condition of the substrate must be carefully analyzed before actual cleaning can commence. |
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Abrasive Cleaning Various Cities, Various Counties, California Review of Various Methods of Abrasive Cleaning Sometimes, despite our best efforts, we are forced to use an agressive cleaning solution when gentler means prove ineffective. Here a sand (silica)-injection unit has been added to a standard 2,000 psi pressure washer to remove old Portland-cement mortar from a limestone artifact prior to reinstallation. |
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