or the best finishers, applying specialty materials becomes second nature, whether quartz, pebble, glass bead or polished marble. The craftsperson and supervising foreman are closely attuned to the product’s nature — how it must go on, how it dries and when to work it. The trowel seems to be an extension of the finisher’s arm.
When done well, the results are stunning: The pool has a monolithic, flawless skin. Apply the product incorrectly, and you might need to start over.
The following guidelines will help you achieve the best finish.
1 Use enough people on the job.
The challenge: Once you start applying most finishes, you can’t stop until the pool is done. Without the right number of people on board, you won’t be able to keep up with the material as it sets.
The solution: When staffing the project, start with the most obvious consideration: pool size. An average shell with, say, 600 square feet of water surface and 105 perimeter feet, will take at least five people, says Scott McKenna, president of Gardner Pool Plastering Inc. in El Cajon, Calif.
Deeper vessels will need more finishers because depth adds more surface area to the project. Features such as steps and benches take more time and skill and may require a dedicated craftsperson. It may take two to handle an extra-long set of steps. Spas, which have a ton of detail packed into a tight space, may require a person working just on them.
Estimate how quickly the material will set and staff accordingly. Warm, dry weather and exposure to sun will speed up the process, so you’ll need more people to keep up under those conditions. Dark finishes dry faster than light ones.
2 Soak the shell first.
The challenge: You don’t want anything to leach moisture out
of the mix, including the gunite or shotcrete underneath. If the shell has been sitting for a long time, wasn’t properly cured or has dry soil behind it, the thirsty concrete can be prone to pulling water out of the finishing coat.
The solution: Before doing anything, hose the pool off until it holds moisture. Chances are, you’ll need to do this several times throughout the process, especially in warm, dry areas.
Watch the shell hydrate. It will help you decide which additives to use and how quickly you’ll need to work. “If what you just wet down looks like you didn’t even touch it, you know you’d better get the retardant out,” to prolong setting, says David Cook, president of David Cook Plaster Co. in South Windsor, Conn.
3 Don’t rush.
The challenge: Many of these products dry faster. If regular plaster takes 30 minutes to set, a quartz finish with a high concentration of aggregate may only take 15 or 20.
Unlike plaster, you can’t add water and manipulate it once it starts hardening. “When that stuff dries, you’re all done,” Cook says. “No human is going to move it.”
The solution: Slow down the mix. In quartz products, hold back on the calcium chloride or other accelerators, particularly if you’re using a high concentration of aggregate.
Cook will cut accelerator use by half or more compared with plaster. You’ll still finish the pool in about the same time as if it were being plastered, he says, because the material will set quickly on its own. In pebble mixes, you might need to use retardants. “That’s pretty much pure cement and rock,” Cook says.
“We go by the rule of thumb of figuring out how long it’ll take you to do the job,” Cook adds. “If it’s a 31/2- or 4-hour job, we then try to figure out how you can do it in 41/2. It’s a marathon, not a sprint.”
4 Tailor the mix for each batch.
The challenge: Materials may behave differently throughout a project, depending on what section you put them in, what time it is and other factors affecting their setting rate. Weather can change drastically as the day wears on, and some sections of the pool may be drier than others.
The solution: Modify each batch to meet its own circumstances. Are you working in the shade? You might want to add more accelerator. Has the sun come out? Retardants might be best.
If you need six batches to cover the pool, expect six slightly different mixes, Cook says. In addition, consider which coat it is. Some want a quicker-setting bond coat so they can move on to the finish.
5 Apply the material thicker than plaster.
The challenge: If you want a high concentration of aggregate to show, you can’t just expose what sits on the surface after you spray it on. You’ll have to press back on two or even three layers of stone, so you can cram enough together. You can’t do this with a thin layer of material on the shell.
The solution: Whereas plaster is usually placed about 3/16 -inch thick, you want closer to 3/4 inch for pebble and somewhere in between for smaller aggregates. This gives you more pieces to press together. Be sure to mix the mud slightly thicker than you would plaster. That way, it will naturally go on in a thicker coat. The extra cement will also help hold the dense aggregate in place.
6 Do detail work early in the day.
The challenge: Benches, steps, fittings and spas require extra time and patience, compared with walls and floors. You need a more precise hand and sense of timing.
The solution: Put crews on detail work early in the day. Your finishers will have fresher minds and bodies, and the cooler temperatures will buy extra time before the material sets, says Jay Eaton, general manager of Cal Plastering Co. Inc. in Phoenix.
7 Pay special attention to the floor.
The challenge: Floors don’t usually suffer much abuse once the pool’s filled with water. While the interior is being finished, however, cleat-clad craftsmen walk all over it. Not only that, but puddles can form, making it tough to go through the process of applying the material.
The solution: Prolong setting as long as possible. After all, you don’t want permanent cleat marks. When doing the floor, avoid the scratch coat used on the rest of the shell because it can suck moisture out of the layers that are put on top of it. Then place a thicker-than-normal final coat on the floor so it takes longer to set.
Do the floors last, to enable water from the walls and detail work to go down the drain. If puddling occurs due to a poor slope on the floor, continuously move the water to the main drain. Most professionals use leaf blowers throughout the floor, and sponge rollers on steps and other smaller flat surfaces.
8 Leave a clean finish against boulders.
The challenge: A boulder has an irregular surface, but that doesn’t mean the material can sloppily bump against it. You want as clean a finish against the rock as you would against a fitting.
The solution: To create a clean line, tape the boulder off around its perimeter before applying the finish. Work the material right against the rock, using pieces of plastic or other instruments that can function as tiny trowels. Don’t try to gradually feather the product into the rock, but press a thick coat against it.
“You need a surface to tee into,” says Alan Smith, president of Alan Smith Pool Plastering Inc. in Orange, Calif. “It has to butt into something. It can’t just blend into nothing because the [aggregate] doesn’t just go from 3/4-inch-thick down to nothing. It has to go straight into the rock.”
Work the finish tightly against the boulder and press it in so it’s flat. Then wash it well. Don’t let it curl up over the edge or it will look sloppy.
