Bond Coat Equals Hollow Plaster

Bond Coat Fail

What is bond coat? Bond coat is supposed to be a polymeric bond agent intended to provide a solid substrate to secure the new plaster to the old plaster. The National Plasterers Council (NPC) states bond agents should not re-emulsify and must be installed per manufacturer’s instructions.

Why does G&B Tile and Plaster (G&B) say bond coat equals hollow plaster? There are several reasons bond coat equals hollow plaster and some of them will be touched on in this post.
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The first issue is the bond coat itself. There are more homebrew bond coats used than manufactured bond coats. What is a homebrew bond coat you ask? A homebrew bond coat is one that is made by a company using materials that are not designed to be used under water (such as mortar admixes) instead of using a manufactured bond coat that has test data supporting its use under water. As previously mentioned above, the NPC states bond coats must “not re-emulsify” and the “applicator must follow the manufacturer’s directions”. Since there is not a manufacturer in a homebrew bond coat there are no directions and this product is definitely not supported for use as a bond coat.

If you hire a company to replaster your pool and they use a homebrew bond coat, you will be on your own when it fails. You should never allow someone to replaster your pool with homebrew bond coat. Otherwise you will learn quickly why we say bond coat equals hollow plaster.

In G&B’s experience, low bidders always use a homebrew bond coat and offer a unique warranty when it relates to the plaster install. These plaster applicators offer a 1-year workmanship warranty. Here at G&B we like to politely call a 1-year workmanship warranty code for a “tail light guarantee.” This means your 1-year workmanship warranty is gone when you can no longer see their taillights as they drive away from your home. This equals to you, the customer, no longer having any sort of warranty. Choosing the low bidder, you will learn quickly why we say bond coat equals hollow plaster.

What about a manufactured bond coat you ask? While it is true manufactured bond coats are designed to be used under water and have test data to support their use, there is no guarantee your plaster will not go hollow. In general, the workers that prep pools for replaster are generally in a rush to get in and out of the pool (and on to the next job) versus being focused on the details and instructions. Manufactured bond coats require their directions for the install of the bond coat to be followed to achieve the product’s proven results. Manufactured bond coats must be mixed and installed exactly as the written instructions on the packaging. Using too much water or not allowing the material to set for the required length of time before installing the plaster can cause failure. The instructions also specify how long the material must cure prior to plaster installation. A bond coat should not be installed in a sporadic method with partial covering of the existing plaster. Bond coats are designed to cover 100% of the existing plaster. Do not install it to look like this.

Improperly installed manufactured bond coat. This is called dashing and will result in bond failure at some point in the future.

It’s important to keep in mind, the same weather concerns that affect plaster application also affect bond coat application. If it is too wet, windy, or cold to plaster; it is also too wet, windy, or cold to install bond coat. In addition, bond coat manufactures require a specific number of days for the bond coat to cure after installation before the plaster can be installed. Most plaster applicators do not adhere to the manufactures’ instructions.

Next comes the issue of friable plaster. The NPC also states you must remove any loose and friable materials prior to installing the bond coat. What is a friable material you ask? See attached picture. Does the person quoting you to replaster your pool know what friable materials are? You should ask them. If they are not able to explain what this means, but are attempting to sell you on replastering you pool then isn’t it a pretty good idea that the crew coming out to plaster your pool doesn’t know what friable material means as well? Friable materials are loose flakes of plaster that are exposed in pool plaster when the cream layer is deteriorated. This scenario is very common on pools that need replastering.
The only way to remove friable material in plaster is to power wash the surface with 10,000 psi, sandblast the surface, or to #hydrodemoreplaster prep the surface. Acid washing will not remove the friable plaster. If you install bond coat over the loose and friable surface your bond coat and plaster will fail in the future. Why? There is not a true solid surface for the bond coat to adhere to.

A simple test to determine if the surface is friable is to scratch the surface with an old key like in this video.

If you get any white flakes on your fingers, then you have friable plaster. Friable materials left on the surface will cause all bond coats to equal hollow plaster when they are not removed. Make sure the company you hire removes all loose and friable material.

The third issue is how many layers of plaster are present in your pool? Were those other layers of plaster currently in your pool installed according to the NPC standards for bond coat listed above? No plaster applicator truly has no way of knowing the answer to this question.

If plaster layers are not removed down to the original plaster layer, you are gambling that your new plaster investment won’t develop debonded plaster. What is debonded plaster you ask? Think of multiple layers of plaster like multiple layers of shingles on your roof. If your roof was leaking and had bald or damaged shingles would it make sense to cover up that leaky layer with a new layer of shingles? Of course not! You want to remove those layers and install the new layer of shingles directly on the roof sheeting. Hands down that is the best thing for a roof. That is also the best thing for your pool. You need to install the plaster directly on the shotcrete shell. Not over a leaky deteriorated plaster job that potentially has 1 or 2 more of the same deteriorated type of layers beneath it.

The last issue G&B wants to point out about bond coat is the lack or false sense of confidence it creates. If plaster companies truly believed their process was the best, why is it they only offer a 1-year warranty? This is a warranty that does not even guarantee the bond of the plaster to the substrate. Why is that acceptable? You, as the customer has made the decision to make a sizable financial investment in your backyard…is a 1-year warranty enough? G&B does not.

A large successful pool plaster applicator in California prepped all their pools with a manufactured bond coat. This plaster applicator installed the bond coat exactly as directed. They believed in their process and had used it for several years. Something changed…the plaster applicator had issues develop in several pools; five (5) months after install the plaster began debonding in several pools. When the plaster applicator contacted the manufacturer, the manufacturer did not stand behind their bond coat. They claimed the plaster applicator caused the problem. The plaster applicator had used this particular bond coat in far more pools than in the ones that had failure (from a bond coat aspect); and interestingly saw each of these pools fail around the same length of time after install. The plaster applicator ended the relationship with the bond coat manufacturer based on their lack of support and their NOW belief that bond coat equals hollow plaster.
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Crack Repair


What do you do if you had crack repair done with epoxy injection on your pool and it failed?

First, you must consider if other options were presented and did the crack repair company give any insight as to what might have caused the cracks? There are several reasons why the pool may have cracked in the first place. Pool cracks are generally a symptom of a larger problem with the pool. To properly repair a cracked pool the issue that caused the pool to crack must be identified and corrected. There is not a “one repair fits all” in regard to pool crack repair. Experienced companies will inspect the pool to identify the best repair methods and then provide you with some options. If a crack returned, it is either due to the wrong repair method being used or possibly the issue that caused the pool to crack is still present.

Epoxy injection repair is limited by the crack it is repairing. If the crack is not clean inside the crack, the epoxy will be bonding contaminated walls of the crack together, not the pool shell.  There essentially is nothing repairing the crack if that is the case. This is the case in most pools over 5 years old. Epoxy injection should not be done without also including staples in the repair. Most staples on the market are about as good as epoxy inside a dirty crack. They are worthless. G&B uses our own proprietary staples. We use a process like no other company with our staples. We open up the pool shell with our Hydro Demo process where the crack is located and find the structural steel on each side of the crack. G&B then saddles the steel with our G&B staples and secures it in place with epoxy. G&B’s staples are then tightened to put post tension strength on the shell along every 12” of the cracks. That same crack is also epoxy injected for a double repair effort. Keep in mind if the pool shell is sitting on unstable soil there is another option that must be utilized. If not the crack repair will likely fail regardless of the use of G&B staples or not.

Crack Repair

Pool Patch Manufactures



Pools crack for several reasons… but how do you repair them? To understand who you should hire to perform crack repair in your pool you must understand these simple issues.  First of all, there is no such thing as “just a plaster crack”. All pool cracks are structure cracks. Second all pool cracks leak. It may not be a fast leak, like a tub drain, but it definitely is a leak. It should be dealt with sooner rather than later. The pool gunite or substrate is not watertight. If the plaster has a crack, it means the pool has a leak.  Once the plaster is cracked the pools’ ability to be watertight is compromised. There is an exception, homebrew bond coats allow the pool water to separate the outer plaster from the under plaster layer. When that happens a debonded hollow spot in the outer plaster layer can crack due to pressure from the water between the plaster layers. These cracks generally look like spider webs or crow foot pattern cracks. Homebrew bond coats do not work.

 Pool crack repair cannot be done with much success without understanding these issues. Most repair techs offer epoxy as the repair option, these same companies also use homebrew bond coats.  To understand how to successfully repair pool cracks you must realize that the crack is always a symptom of a larger problem. If you simply repair the crack with just epoxy you most likely will not be addressing the issue that caused the crack at all. There is a very good chance that epoxy alone will not repair a crack at all. Pool water has Total Dissolved Solids. A crack that is leaking will have that same TDS inside the crack. The epoxy works well, only if it bonds to clean concrete. The likelihood that a pool crack in 5 year old pool will not be contaminated is slim and none. It definitely won’t be clean concrete. That is why most techs include a coat of polyurethane over the crack repair in case the epoxy fails. This is also why crack repair with epoxy should not be done without also incorporating quality staples.  G&B uses our own propriety pool staples for crack repair.  They are the only staples on the market that properly address the goal of including staples in crack repair.

Introduction to Repair of Pool Cracks



Pool cracks develop for several reasons, such as:

  • Inadequate bearing of the soils or soil related issues. Pools are built all of the time without anyone even considering the soil in which the pool is built on.  Consider the weight of a diving pool.  A diving pool can hold +/- 30,000 gallons of water, with the water alone weighing +/- 240,000 lbs.  When you consider all of the construction material and the water, a diving pool can weigh in excess of 450,000 lbs.  The reactive soils in North TX assure most pools will be built on soil that is not suitable for the pools weight unless the soil is properly prepared or construction efforts are in place to deal with the soil issues.
  • Inadequate tensile strength, and/or lack of, or improper placement of reinforcing steel. The rebar installed in older pools varies on its placement. I have seen rebar installed in larger than 10”x10” on center grid patterns which is bad. 8”x8” on center grid pattern is standard in today’s pools.
  • Inadequate compressive values of the gunite. Gunite application can be great and perfect for pool construction, as long as all rebound and trimmings are thrown out of the pool during construction. The reality of that is that the total cost would increase if that were done. So most companies do not throw any of that dead material out. It winds up in the pool floor, steps, and benches of the pool and spa. There is no compressive strength to rebound and trimmings. The areas of the pool that have rebound in them have no compressive strength and the pool structure is weak in that same area.

Add water loss or improper drainage to the equation and the above issues are compounded. Pool cracks consistently develop under skimmers and it is always due to a leak in the grout where the tile meets the actual skimmer. If you are losing water in your pool, it must be considered a major problem. You must be in control of the water in your pool. When you have a leak, it will soon be in control of you.

G&B does not use the same repair methods that every other company offers. We understand and respect the power of water.