High Pressure Water Cleaning is a relatively new method of cleaning newly-constructed masonry, although it has been used for many years in masonry restoration work.
The more sophisticated high pressure cleaning systems feature a high pressure gun and nozzle with remote control switch allowing an operator to automatically apply cleaning solution while operating the gun several hundred feet from base unit. Other systems provide two separate hoses, one with plain high pressure water and the other with solution of cleaning material, also under pressure. Care must be taken in selecting cleaning material compatible with the pumping equipment as recommended by pump manufacturer.
All units must be portable in order to be taken within close range of job. Compact units are mounted on skids, wheels, trailer, etc. More elaborate systems are truck mounted, complete with pump, engine or motor, cleaning material containers, water storage tank, and water heater.
Nozzle pressures generally range between 400 PSI and 800 PSI. However, many available units are capable of producing pressures well over 1000 PSI and should be used with caution. Flow is normally between 3 and 8 gallons per minute.
Many cleaning contractors are using high pressure systems in an effort to reduce high labor costs associated with traditional cleaning systems. Most contractors agree the high pressure system is more efficient. However, hand labor is still needed to remove large mortar particles from the wall surface before applying water and cleaning solutions. Also, extreme caution should be used in applying cleaning solutions under high pressure. This practice is economical but could be harmful to the operator, to adjoining property, and could drive the cleaning solution further into the wall than is necessary for surface cleaning, causing further staining.
Cleaning solutions may be applied more effectively and safely by brush or by low pressure (maximum 40 PSI) orchard type sprayer.
In many cases, high pressure water without any special cleaning materials will successfully clean new masonry walls. When hot water is used, high pressure without chemicals is even more efficient. High pressure water cleaning may be used on most hard burned, textured clay brick. This includes reds, buffs, grays and other through-the-body colors. However, it is safest to keep pressure well below 1000 PSI when cleaning buffs, grays, etc., since these colors are more susceptible to mineral oxidation which could be aggravated by excessively deep penetration of water. Also, high pressure water cleaning should be used only with approval of brick manufacturer.
This system is generally acceptable for cleaning lightly sanded or sandblast textures where a fine application of sand is well bonded to the brick body. Caution should be exercised in using high water pressure on slurry or "sandblast" textures where an excessive coating of sand adheres loosely to body. High nozzle pressures may cut streaks in the relatively soft sand facing.
High pressure water cleaning may be detrimental to handmade brick and any underburned product. Also high pressure water can erode mortar joints.
The following procedure is recommended for High Pressure Water Cleaning:
- Wait for mortar to harden, but cleaning with high pressure water should not start before mortar is seven days old.
- Remove all large mortar particles with hand tools before applying water or cleaning solutions. Use wooden paddle, the rough edge of a brick or metal scrape hoe. Chisels may be used, if necessary, to remove hardened mortar or concrete. This "pre-cleaning" is a very important part in cleaning new masonry. Don't expect cleaning materials and/or water alone to remove large particles of hardened mortar. These can only remove thin smears.
- Mask and otherwise protect adjacent metal, glass, wood, etc. surfaces as recommended by product manufacturers.
- Saturate wall with clean water. All immediate areas to be cleaned must be saturated as well as masonry areas below.
- When wall is completely saturated, apply cleaning solution, starting at the top of wall. Solution should be approved previously by architect/engineer and brick supplier. Concentration should be as recom- mended on container. Solution may be applied to wall with masonry cleaning brush or low pressure (maximum 40 PSI) sprayer. Application of cleaning solution by high pressure should be previously approved by architect/engineer and brick supplier. Fifty degree nozzle is generally recommended for applying cleaning solutions. Let cleaning solution remain on wall for 3 to 6 minutes, or as directed on product label.
- Rinse wall with high pressure water from top to bottom so all dissolved mortar particles will be completely flushed from wall surfaces. The most efficient sprayer is the fan type, stainless steel tip, dispersing a 25 degree to 50 degree fan spray. Never use less than a 15 degree fan spray tip.
(Test clean a sample area to determine effectiveness of cleaning compound and the total cleaning system and to check wall for possible damages caused by system. Approval of owner or owner's representative should be obtained before proceeding with operation.)
Courtesy of GoBrick.com