In this article I will help you make an informed decision on resurfacing the interior finish of your upcoming swimming pool construction or renovation project.
The “interior finish” is considered the finish on the walls and floor of the pool below the tile line. For in-ground gunite swimming pools and spas, this may be a plaster or tile finish. Of recent, mosaic glass tile has become very popular for swimming pool interior finishes, but is usually reserved for specific applications and only recommended for particular areas of the world.
In the pool industry; the term “plaster” may be used to describe standard plaster, quartz plaster, pebble plaster or a variation which can include glass beads or some kind of hybrid plaster. The most commonly used finish is standard white or grey plaster; this is because it is the most cost effective option. There are a few more things to consider, other than price, when making the decision about how the interior of your swimming pool will look and function. Let’s take a look at each of our options for interior finishes to help make our decision. We will try to keep this informative and not to clinical.
Standard White or Colored Plaster Finish:
Standard plaster is basically made of white cement and crushed marble. Standard white plaster is the original plaster which was used on your grandparent’s pool. Standard white plaster gives the pool an inviting light blue hue and a classic look that will stay white with proper maintenance. Standard plaster is the smoothest finish of all plaster types.
Standard plaster is considered by the National Plasterers Council as a “soft” product when compared to other finishes. Standard plaster is hand troweled like all other interior finishes, but will tend to show trowel marks more easily. Standard plaster is more susceptible to damage from imbalanced pool chemistry, which can result in slight shading, scaling, staining, etching, cracking or delaminating in extreme cases. Standard plaster will have the greatest chance to change appearance over time.
There are hardeners called “pozzolans” which can be added to the plaster mix. Pozzolans change the chemistry of the cement and make the plaster more impervious to the effects of poor chemistry. There are also silicon additives which can be added to help maintain the plaster finish. There is an additional expense to additives and it is not a complete solution to countering the effects of pool chemicals and environmental effects on your plaster.
Standard plaster can also be colored and it is commonly referred to as just “colored plaster”. Simple huh? Colored plaster is white plaster with colored pigments added in the mixer before application. Colored plaster can be any color but don’t expect an exact match from a color sample. Colored plaster will usually change color and fade over time. The most popular color is varying shades of grey.
There are numerous complaints about colored plaster, which in turn has led many companies to discontinue this option as an interior finish. Those that do offer it will have you sign a long disclaimer about all of the inconsistencies involved with colored plaster. Here is a list of common complaints about colored plaster, which are considered acceptable by plastering standards: mottling, pigment stains, streaks, unevenness of color, variation between color and sample, checking and crazing.
Checking and crazing refer to a type of superficial cracking that looks like the spider cracks on aged china dishes. In fairness, all plaster finishes will eventually develop some degree of checking and crazing, but it is more easily seen in colored plaster.
If you are still interested in colored plaster, then you will enjoy the patina/mottled look with a beautiful colored pool, as well as save some money over the other finishes.
Quartz Finish:
Quartz finish has gained popularity because it is a very durable finish, but costs less than pebble finishes. Quartz plasters are made by several manufacturers and each has a different claim about how their plaster is better than the rest. Any plaster is only as good as the company installing it and a reputable company will use a product in which they can stand behind.
Quartz plaster is made the same as standard plaster, but the sand is replaced with crushed quartz stone. There are polymers offered to strengthen the mix; in place of the pozzolans used in standard plaster. Quartz stone is both a very hard and dense stone, but a big difference is in the application.
After the plaster is troweled and the curing process begins, special water nozzles are used to strip the top layer of the plaster surface away. By doing so, this exposes the quartz within the plaster and gives the surface a more durable finish. Colored quartz stone can be added to the mix for a different look and the base plaster can be colored to give the pool a beautiful look.
Many of the concerns with standard colored plaster are not a problem with a quartz finish because the top layer of plaster has been stripped away. This gives the plaster a greater color consistency and less issues with the appearance of crazing. Quartz finishes are very smooth and have a similar look to standard plaster.
Pebble Finish:
A pebble finish is known in the industry as an aggregate finish. A common misinterpatation in the pool industry is to call a pebble pool finish “Pebble-Tec”, but that would be like calling every pair of jeans “Levi’s”. Pebble-Tec was the original company to patent the process and has the greatest recognition, but just like the quartz finishes, there are many manufacturers who make pebble or aggregate finishes.
A pebble finish is obtained much like a quartz finish. Small polished stone is added to the plaster mix (usually a standard plaster) and hand troweled onto the gunite pool surface. As the plaster starts to cure, special water nozzles are used to strip the top layer of plaster away, which exposes the pebble. A big difference here is that the majority of the surface is all stone as opposed to a quartz finish where it is a mix of plaster and quartz.
The pebble finish when complete, is a solid layer of polished stone with the colored plaster mix peeking through the space between the stones. Each manufacturer offers different sized stones to give each pool a different look. Some stone is colored, whereas others have more consistent shades.
Pebble finishes are rich in color and have subtle color changes with the depth of the pool. A tan color shows the most dramatic change in color. The shallow steps will show the true golden tan color, but as the pool gets deeper the water takes on a beautiful emerald color.
Pebble finishes are superior in durability. The exposed surface is made-up of solid tumbled stone. They are impervious to fading and chemical reactions. Aggregate finishes also have a long track record, so you should not feel as if you are testing out new technology.
As with the other interior finishes, there are additives to strengthen the plaster behind the pebble. Similar aggregate finishes are now available which contain glass beads or other materials like abalone shell.
You have probably already guessed that this option is the most expensive. The cost will be over double the cost of standard plaster, but this where you need to consider the longevity and aesthetics of pebble over price.
The process of choosing your pool's interior finish should be both fun and gratifying. On one hand, it brings out the designer in all of us. On the other, it will tie in your outdoor pool environment for years of family fun. Ultimately, the choice is yours and should be based on preference. There truly is an interior finish and color for everyone!