G&B Tile and Plaster

Tips for blast off

High pressure water jetting is relatively easy and safe, with the proper precautions and steps. Here are some key points:

Suit up

With water hitting the surface at such high pressures, chunks of plaster will fly around the site during the jetting. Even more importantly, the machinery can cut through people.

“It’s more than just a pressure washer,” says Bob Chiapelli, president of Poolside Plastering near Philadelphia. “Even a 3,000-psi pressure washer ... can cut you with the right tip on it. But with these 40,000-psi machines, if you’re not careful, you could take a leg off. They will cut through steel.”

Because of this, workers should wear masks, rain suits and steel-toed boots — and perhaps even shin guards.

Consider tenting the site

The pieces of material that fly around are generally no bigger than a pencil eraser. However, if the water jet hits an area that has begun delaminating, larger sheets can come off.

To keep the property clean and protect windows and outlying features from damage, these professionals sometimes create a tent around the pool. This is often necessary in indoor pools. “[The system] does let off a lot of steam,” Chiapelli says. “It’s not the dust that you would get with the sand blaster, but it throws up steam and particles. And when you’re taking plaster completely down to the shell, that’s a lot of plaster.”

The tent should be made with a tightly woven mesh-type material so it will catch almost everything while allowing steam and air to travel though. To create the tent, Musgrove and his crews stretch a large debris net across the pool and raise a tall pipe in the middle. “Think of the big top in the circus,” he says.

Begin by checking the equipment

To protect workers and equipment, crews should begin by checking hoses and major parts before running the system at each site.

“You don’t want leaks because it’s dangerous,” Chiapelli says. “If you have any kind of problem, you want to stop and repair it before using anything. A hose can blow, and with that much pressure it can kill you, not to mention cause damage to the property.”

Check from pump to nozzles to make sure the hoses are in good shape and that all the connections are solid.

Familiarize yourself with the feel of the nozzles

There’s no big trick to the actual jetting itself, these professionals say. Musgrove likens it to washing your car at a do-it-yourself stall.

Decide what kind of angle works best for the application. Schilli likes to position the nozzles so they’re perpendicular with the target, imposing the full force of the water. But if keeping the grounds as clean as possible is the main concern, crews should do their best to point the jets slightly down, which helps contain splash out and debris inside the shell.

Make provisions for water removal

These professionals like etching with water because it’s much cleaner than sand. The runoff, however, is filled with plaster dust and debris.

For this reason, left over water cannot be released into the sewer, gutter or in the landscape. Some kind of separation tank should be created. To do this, some professionals use the slurry bags used when applying pebble.

“Basically they’ll set the slurry bag on the driveway, on the street or near a sewer, and the water drains out of it,” Schilli explains. “We go back after a day or so, and everything inside is kind of dried out. They just take the bag, throw it on the truck and haul it off. So we’re actually containing all the waste into those bags. We bring them back to our warehouse, throw them in the dumpster, and they’re hauled off to the landfill.”

 

Like every pool professional in the nation, Greg Musgrove was looking to differentiate his company. One way is in how he prepares pools for resurfacing.

The company Musgrove owns, G&B Tile and Plaster Ltd., is based in the Dallas-Fort Worth area, where many local competitors use so-called “home brew” bond coats. These plasterers formulate mixes onsite, often with cement, sand and an inexpensive acrylic or concrete glue, rather than use a pre-manufactured product.

Rather than try to explain the difference between the products he used and the home brews, Musgrove chose to step completely out of the bond-coat discussion. Instead, he now uses water jetting to remove unwanted finish material from existing pools and spas, as well as to etch the surface in preparation for the new coat.

Though the change is much more steak than sizzle, it has paid off for Musgrove. “It’s about how you tell the story,” he says. “When you compare going on top of a finish with a bond coat to preparing a surface with up to 40,000 pounds per square inch [of pressure] … it’s easy for us to sell that difference.”

The system is gaining popularity, but it means different things to different applicators.

Here, learn how water jetting works and the ways in which some plasterers are using the technology.

The basics

Water jetting, also called water blasting, uses a pump to push water through a hose and out a jetted wand at high pressure. The concept was adapted for the pool and spa industry fairly recently, but has long been used for purposes such as paint removal and pipe cleaning.

Some professionals rely on water blasting to remove one or more layers of plaster, while others just use it to remove paint or to etch an existing surface.

Systems vary in the amount of pressure they can exert, typically ranging between 10,000 and 40,000 psi. The lower pressures generally are suitable for removing paint and etching the existing plaster’s surface. The highest-pressure systems allow professionals to do more intense etching, so some companies feel comfortable bypassing the bond coat altogether. They also can accommodate more than one worker.

“You can use two wands at the same time with a 40,000-psi system, so you can get it done twice as fast,” says Bob Chiapelli, president of Poolside Plastering in the Greater Philadelphia area.

Ultra-high-pressure systems also move the water so quickly that it creates heat, which makes the pool cleaner. “The water, because of friction … reaches 180 degrees,” Musgrove explains. “So you’re cleaning with very high pressures and very hot water. You can’t get a better clean than that.”

Some plasterers, particularly those using 10,000- or 20,000-psi models, may still want to add the bond coat to help fuse the new material to the substrate. In those cases, the water jetting replaces sandblasting as a means to prepare the surface for the bond coat.

“[The manufacturer] has told us that as rough as it is, you really don’t need to put on a bond coat,” says Dave Schilli, president of Schilli Plastering Co. in St. Louis. “But for the couple hundred dollars that you spend in bond coat material and application, it’s just not worth it, in my mind, to be taking a risk.”

Replacing the sandblasting process was a primary motivation for Schilli to purchase his 20,000-psi system. “It seemed like a great idea, because it was so much cleaner than sand,” he says.

He actually started out with a 10,000-psi system, but converted it to be more powerful. “What it came down to was the efficiency, whether it would be powerful enough to prepare the surfaces as we expected them to be,” he says. “As it turned out, the 10,000-psi … was adequate, but I wasn’t really comfortable with it. When we converted a 10,000-psi to a 20,000-psi, we were able to roughen up the surface a lot easier, a lot better.”

These professionals also report that the process is much faster than the other options. With the 40,000-psi system, Musgrove’s crews often can prep and plaster a pool in a day. “When I would use a bond coat in a pool that’s painted, it would take me 2 to 2½ days to get the pool prepared,” he says. “Because I would one day sand blast it, then clean up that debris, and then I’d come back the second or third day and do the acid wash and the bond coat. With a water jetting machine … on a pool that’s been painted, I can prepare it in the morning and plaster it in the afternoon the same day.”

For those professionals who choose not to apply a bond coat, weather becomes less of a factor, since there’s no concern about how the temperature or humidity will affect the formula.

The investment

But all the convenience of this method comes at a cost.

For Musgrove, that cost was $140,000. Schilli paid north of $80,000 when he purchased his 20,000-psi system approximately seven years ago.

And the work wears hard on the machinery, so there is quite a bit of parts replacement in a year, says Chiapelli, who estimates annual replacement costs at $10,000.

The addition of a water-jetting system also may require a close look at staff. “Water jetting requires a different mentality than just spraying on bond coat,” Musgrove says.

First, there’s the comfort level. For safety reasons, crews must wear a rain suit and head gear. Combine that with the water’s temperature of up to 180 degrees coming through a 40,000-psi system, and that can be an unpleasant day.

Water blasting also requires more attention to detail than the other methods. There are safety considerations for handling a water jet that’s strong enough to cut through concrete. Even more tenuous are the parts and equipment that must endure all that pressure. For instance, because manufacturers understand the kind of abuse on the hoses, they often don’t offer a warranty for those parts, meaning crews have to be very careful to protect the sizable investment.

“It cannot be overstated how fragile the equipment is,” Musgrove says. “The hoses are 50 feet long and cost $2,000 apiece. That hose can fail in 10 hours if your guys are just throwing it around.”

Because of this, he says, he spends as much time supervising his water-jetting crews as his plaster professionals.

The investment in staff also can increase. “My water-jetting crew makes as much as a plaster crew does,” Musgrove says. “The foreman on a water-jetting crew makes as much as a foreman on a plastering crew.”

And where sometimes a single worker could bond coat a pool, he uses a three-person crew for water jetting — one to run the pump and two to perform the jetting.

But these professionals have found that the investment makes sense. For Schilli, the equipment paid for itself immediately. In the last year he worked with a sandblasting contractor, he paid approximately $160,000.

“So the savings alone [make up for it],” he says. “Plus I can control my schedule better now because I’m doing it in-house.”