One theme that runs across all coating project types and substrates is the importance of surface preparation. According to coatings manufacturer Sherwin-Williams, up to 80 percent of all coating failures can be directly attributed to inadequate surface preparation, which can affect coating adhesion. Improperly prepared surfaces often result in reduced coating integrity and service life. As such, the ideal method of surface preparation depends on understanding and adapting to factors such as the substrate, the environment, and the expected life of the coating system.
“The bigger the job and the more ramifications of something failing, the more scrutiny that gets put on it,” said Brian Cappallo, business development manager for technical services at steel abrasives company Winoa.
While surface preparation is often seen as one aspect of a broader coatings application project, there can be numerous steps just within that one phase. Factors to consider may include safety protocols, climate control, and pressure washing — just to name a few. To assist in finding proper solutions, CoatingsPro Magazine put together an updated guide for 2020 to help contractors discover the best and latest tips for surface preparation success.
Before starting any physical surface preparation work, contractors should take time to develop a suitable plan for all jobsite safety requirements, both for workers themselves and the surrounding areas. Given recently enhanced regulations from the U.S. Occupational Safety and Health Administration (OSHA), this step has only become more important entering the 2020s.
“OSHA requires employers to use a hierarchy of controls where there are substitutions or eliminations at the top of a hierarchy,” said Mark Tartaglia, senior CIH (Certified Industrial Hygienist) consultant at DuPont Personal Protection. “This is often difficult, so then you step down into engineering controls and then work practices. PPE [personal protective equipment] is really the last line of defense.”
Ideally, many hazards could be engineered out of a project. But for the construction industry, where most tasks are completed directly at the jobsite, this may not be possible. This leads to a priority on PPE, with a customized plan for each jobsite.
“It starts with doing a comprehensive hazard risk assessment for each job,” Tartaglia said. “From a PPE perspective, where I can comment the most, it would be things like garments, gloves, and respirators. But it could also be fall protection. It really needs to be a broad, comprehensive risk assessment that takes into account the different types of exposure, including physical hazards such as falls from heights; slips, trips, and falls; cuts and abrasions; as well as chemical exposures, exposure to hazardous particles and liquids, etc.”
Within PPE for surface preparation, type-CE supplied-air respirators approved by the U.S. National Institute of Occupational Safety and Health (NIOSH) are often essential. Other needs are often blast hoods, gloves, eye and ear protection, coveralls, hard hats, and boots. Depending on the jobsite location, fall protection from providers such as 3M and Guardian Fall Protection may be required.
DuPont offers a variety of protective coverall garments through its Tyvek and Tychem brands. “Both Tyvek and Tychem garments would be appropriate for coatings contractors because a lot of the coatings products are chemical-based, complex mixtures,” said DuPont’s Tartaglia, whose company introduced a new line of protective gloves in 2019. “DuPont provides a range of glove options for painting and coatings applications, including nitrile, neoprene, and butyl,” he explained. Other PPE apparel providers are Superior Glove and Warwick Mills.
Though water is often used to clean a substrate, too much of it can create its own set of problems. For instance, if a contractor is dealing with a leaky roof, adding water may not be the answer. In that situation, equipment such as leaf blowers and shovels may make more sense. And with concrete slabs, excessive water can lead to poor adhesion and premature coating failures.
Wagner Meters and Tramex Meters are among providers of products to test moisture levels in both industrial and commercial settings — including in situ relative humidity (RH) testing. For that objective, Wagner’s new C555 Concrete Moisture Meter is among the company’s latest developments. The C555 emits an electromagnetic wave to measure moisture down to 0.75 inch (1.9 cm) below the surface. When combined with an ASTM-compliant in situ concrete RH testing system, the C555 is a novel targeting system that helps contractors place probes in areas where they are most effective.
Meanwhile, Tramex recently upgraded its Concrete Moisture Encounter CME5 to add features such as Bluetooth connectivity to iOS and Android apps, allowing for continual development and integration of apps and reporting; a robust new enclosure with a rugged, ergonomic design; and an extension bracket and handle to avoid kneeling. The CME5, used as a non-invasive moisture meter for concrete, is now optimized for extended battery life and for combined testing to improve accuracy.
For roofs, contractors should be prepared to remove and replace all water-damaged areas prior to applying new roof coatings or coated spray polyurethane foam (SPF) systems. The Tramex Dec Scanner is one example of a mobile, nondestructive impedance scanner designed to instantly survey moisture conditions in roofing and waterproofing systems.
Once the climate is under control, one common method of surface preparation is to use a pressure washer, which cleans the substrate by removing old coatings and contaminants. Pressure washers can be used on concrete, steel, and roof substrates, with options including cold- and hot-water models and pressures up to ultrahigh-pressure waterjetting.
The choice of pressure washers often depends on the unique needs of each jobsite. For example, while cold-water pressure washers are suitable for handling basic tasks such as removing dirt and mud, projects involving more complex contaminants — such as grease and grime — may require hot-water models. While the gallons per minute (gpm) and pounds per square inch (psi) of pressure of each machine must be strong enough to clean the substrate, excessive pressure can cause its own set of problems by damaging the surface. Thus, contractors have a delicate balance to find when selecting equipment, and they should pay close attention to the manufacturer’s specifications for the selected coating system.
Hotsy, Jenny Products, and Mi-T-M are among the industry specialists offering various cold and hot pressure washers and related equipment. Mi-T-M recommends combining its CBA Aluminum Series cold-water pressure washer with a 20-inch (50.8 cm) rotary surface cleaner. The surface cleaner is described as an ideal accessory for cleaning flat surfaces. “It has strong-bristled brushes for easy glide control, a heavy-duty aluminum handle, and a high-pressure trigger gun for efficient cleaning,” said Karen Anderson, marketing manager.
Preparation Makes Perfect
The diversity of options available across all these niche areas directly reflects how important surface preparation is. By combining that innovative approach with attention to detail on surface preparation, contractors should be able to blast themselves into success in 2020 and in the new decade ahead.
Editor’s note: These are excerpts from our 2020 Surface Prep supplement. The complete roundup, which includes surface prep tips for concrete and steel surfaces, too, can be found online, along with several other articles pertaining to the various aspects of surface prep.