There are two ways to install retaining wall blocks, mortared or dry stack. The cleaning process after installation is exactly the same, with one exception. Mortared retaining walls will need to be scraped between applications to remove the chunks (the mortar will also need time to set prior to beginning the cleaning process).
Testing is always recommended prior to any cleaning project. Although this process has been tested and proven effective, every situation is different and can present different challenges. Allow the test area to dry thoroughly before evaluation of the final results.
After the retaining wall has been installed and before landscaping has begun, follow the below procedures to remove excess mortar, job site debris, and dirt:
Lightly pre-wet (do not soak) the retaining wall surface. * If landscaping is already in place, thoroughly soak the roots and foliage and/or cover with plastic. Be sure to keep landscaping wet to prevent chemical from drying on the surface.
Apply NMD 80 through and EC Jet (or through a pump sprayer diluted 4:1) starting from the top and working down the wall using overlapping strokes to achieve even coverage.
Allow the cleaner to dwell for 5-7 minutes. Do not allow the product to dry on the surface.
Scrape any large chunks of mortar off with an appropriate scraper (if mortar is present).
Re-apply NMD 80 through an EC Jet (or pump sprayer diluted at 4:1) to melt away the remaining mortar smears, job site debris, and dirt. * With NMD 80, the longer it stays on the surface, the cleaner the end results. It has been noted that longer dwell times produce a decrease in the water rinse
Begin rinsing from the top of the retaining wall and work down. Use long even strokes that overlap each other. A thorough rinse is necessary to avoid leaving any cleaning material on the surface or in the retaining wall block. *Rinse pressure is determined by the masonry manufacturer's requirements. Color sensitive surfaces should always be rinsed with low pressure.