Category: Spa Hot Tub Surface Repair


TO: Multi-Tech Products

What would cause this wrinkling during a repair?   (see photo below)

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Thanks,
Ryan

To: Ryan

I could give a more specific answer if you had provided more information. Were you using our MMA system, or the Quick Glaze process? What filler was used? What steps did you take prior to seeing the wrinkling? Did you follow our procedures?

So, I will try to explain all of the potential causes. If you were using the Quick Glaze system, it could occur during the spraying operation.

The Base Coat is first sprayed on the surface, and it contains a hardener that cures the coating. The Clear Coat needs to be applied before the Base Coat is completely cured. Otherwise, the solvents in the Clear Coat will attack the Base Coat, and it can create the wrinkling. The Clear Coat can go on directly over the color. The Finishing solvent can also be sprayed directly on to these coatings.. All of the coatings should be applied consecutively, as quickly as possible. Under normal ambient temperatures, the time window is about 45 minutes. Higher temperatures will reduce this working time. Waiting 45 minutes or longer to apply the Clear Coat will make the Color coatings wrinkle. The retarder must also be used as the reducer for the base color coat for thinning. Against all of our recommendations, some people fail to use the QG Clear Coat. If there is no clear coat on the application, you will need to remove the color by sanding and applying a lacquer thinner to remove all of the coatings before re-applying them, correctly..

These issues do not exist with the MMA system. Furthermore, the operating time windows on applying the various MMA coatings are very flexible

However, the MMA System or the Quick Glaze system can lift or wrinkle a previously sprayed repair. For example, it can occur when an epoxy or other unknown coating was used as the base color spray. However, both systems can work well as a touch up of a complete refinish job unless the refinish coating that was used was an epoxy, or there was no clear coat used..

A less common cause is something wrinkled under the color and the clear coats. It could have been the filler, or you sprayed over uncured resin in the FRP shell? If it is uncured resin with this level of wrinkling, the area would be soft when poked with a screw driver or sharp tool.

Hope this helps.

Rob

 

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To: Multi-Tech Products:
This repair (see pics) was done about 3 months ago and is now turning cloudy. What could be the cause ?
I’m thinking a reaction to spa chemicals?
Doug

IMG_1621 IMG_1622

To: Doug,
It is difficult to determine the exact cause of this problem without knowing some of the history and common water chemistry maintenance practices used on the spa. There are least two causes. Information on them follows.
Here is information on common chemical damage to acrylic spas. I don’t suspect this to be the cause, since issues would occur at other areas of the spa – not just at the repair.
https://multitechproducts.wordpress.com/2014/12/15/surface-discoloration-in-an-acrylic-spa/
The next article describes what can happen to our Clear Coat if it is exposed to moisture before complete curing – normally requiring 24 hours..
I think this is the most likely cause in your case. I am assuming you used the MTP Clear Coat to finish the repair, since we believe it is an absolute necessity to achieve a quality repair.
Three months is normally the time window that post cure repair issues show up.
https://multitechproducts.wordpress.com/2012/06/
The repair could certainly be damaged by strong oxidizing chemicals (e.g. tri-chlor). However, Tri-Chlor would also cause fading in the acrylic in other areas of the surface. So, I don’t believe tri-chlor exposure is the culprit.
If the problem is simply premature exposure to water, it is an easy fix. You just need to remove the repair coating, and respray.
I would recommend sanding with 400 grit sand paper to remove the top coating. Light sanding can remove the damaged Clear Coat while preserving the Color Coat. At least, it could limit the need to spray more of the Color Coat.
After completing the repair, it is very important to keep the repair zone dry for a sufficient time to allow the coatings to completely cure.  Exposure to any form of water may effect the coatings.   If the repair was below the water line, wait for at least 24 hours before refilling the spa.
This communication addresses the post-repair cure procedure, and how to place the cover to protect against water getting on the repair zone.
https://multitechproducts.wordpress.com/2012/07/02/118/
Hope this helps,
Rob

To: Multi-Tech Products

I have attached a photo of a hot tub installed in a hotel. It is a plastered spa, and large chips are coming off of the surface. Can it be salvaged using your FRL System?
Thanks,

Jim
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To: Jim

The quick, simple answer is yes, it can be used to renew the hot tub surface. However, before I give the complete answer on FRL resurfacing of a plaster finished hot tub, I want to address common issues with the practice of using fiberglass coatings over plastered swimming pools. Even though they are the same application, using a fiberglass coating on a plastered swimming pool brings much greater risks for failure than using fiberglass over plastered hot tubs.

There have been companies that specialize in a total refinish of pools by applying a fiberglass composite on top of the plaster. Therefore, there are a lot of these swimming pools in service today that have experienced a high rate of failure. Repairing these failed jobs have great appeal to repair technicians. Even complete pool resurfacing can be achieved with our FRL system. The larger the pool, the bigger the job, and bigger the pay check, right?  Our advice is don’t be quick to jump for that big pool job. Even though it might appear to be a great business opportunity, it is very risky to re-surface plastered swimming pools. Applying fiberglass resin systems over plaster does not always provide for resolution of the underlying issue, deteriorating plaster. These overlays of FRP usually fail as the plaster continues to deteriorate.

The explanation is that although advanced resins are utilized, and the top layer bond is great, adhesion between the different layers of fiberglass, plaster, and concrete base will decline. This leads to complete failure of the composite structure application. Some resurfacing will lose adhesion in big sections, and some will just have small areas that come loose. It is best to refer the major failures to a contractor that will completely re-plaster the pool. On the same note, the smaller failures provide the opportunity for repair professionals.

The following photos show one example of a swimming pool that had been completely over laid with fiberglass, and a partial repair was made, successfully. So, if the plaster has not become too brittle and chalky, a pool with small area(s) of failure can be repaired with the FRL System. It can provide a worthwhile extension to the life of the pool before a complete re-plastering is necessary. However, we would not recommend providing a warranty on these partial repairs.

2013-05-09 10.51.50 Before

2013-05-27 11.43.35After

Your hot tub can be refinished with our FRL system. It would require a complete resurfacing of the entire surface (nothing partial). Therefore, you should not commit without a prior inspection of the empty spa. Based on my analysis of your pictures, the glaze layer of the plaster is peeling. This layer is comprised of about .125″ thickness of the total original plaster finish. The glaze was created as part of the total installation process when the plaster was applied during the original construction.

The primary issue in resurfacing with any fiberglass product including our FRL system will be the ability to achieve prolonged adhesion to whatever you are applying it to – in this case the aged glaze or exposed plaster. But, if you re-surface the entire plastered hot tub, the FRL resin layer acts as a cap over the plaster, although it does rely on achieving a strong, long-term bond to the substrate. Hot tubs are smaller than pools so as the plaster layers deteriorate, the smaller bonding surface areas stay in place for the long-term. Ideally, the smaller volume allows for sufficient structural strength without the need for the strongest substrate composite integrity. Thus, it will stay in place and function correctly as a capped surface.

An inspection would be necessary to determine the condition of the plaster. Plaster fails by becoming brittle and chalky. The core plaster layer is under the glaze and on top of the concrete structure providing the shape of the hot tub. The primary cause for plaster becoming chalky, soft and brittle is from over-use of pool chemicals. So, you should remove the glaze in a few areas, and assess the condition of the plaster underneath, as well.

The FRL resurfacing procedure includes grinding and filling the substrate to assure smoothness, and provide a surface that allows the best possible bond with the FRL resin. That process will expose the core while leaving some of the glaze in place. If inspection confirms that the plaster is hard and shows little evidence of brittleness or chalkiness, then a re-surfacing with the FRL system would be advisable. One advantage of the FRL finish compared to a plaster surface is the ease of cleaning. The surface is much smoother, less porous and will be more durable.

Important Note: Resurfacing over peeling plaster is risky, and should be attempted only with everyone understanding the issues and potential for success or failure.

My experience is that plastered Hot Tub resurfacing with the FRL system has yielded long term adhesion and less call-backs when good judgment has been used during inspection and preparation for the refinishing stages. The same judgment should be used when establishing a warranty.

Rob Clos

TO; Multi-Tech Products

Wow, the before and after pictures of this hot tub are incredible. I’m amazed at how well it was repaired. Is an FRL system pretty common? Or do they use that on the newer hot tubs only? I’m just curious because I’ve got a pretty old hot tub that I need to get repaired.

Thanks Mia

To: Mia

If your hot tub is very old, 30 years or more, it is probably gel coat with a FRP backing, and installed in a cabinet or outside deck.  This type of product is suited well for resurfacing with the FRL system.  Refinishing a gel coat spa will give a permanent finish that will last 10 to 20 years.  The same applies to a spa made with an acrylic surface.  Acrylic spas were introduced in the early 1980’s, and quickly replaced gel coat products, due to superior performance.  These were offered as portable spas, but in-ground models were available.  Older plastered spas, which are frequently built with swimming pools, can also be resurfaced with the FRL system.

The pictures you referred to are actually a pool that was fiber glassed over plaster.  Fiber-glassing plastered pools and hot tubs is pretty common.  Companies that specialize in this service have come and gone over the years.  The business failures have been due to the liabilities from deterioration of plaster as described above.  Resins have improved over the years, which have made a difference in how long the new surface lasts.  But the main issue is that the plaster fails.  The FRL system is unique, and is designed for surface renewal.  It has proven performance in the right application.   See the above article for recommendations and limitations.  FRP is the acronym for Fiber Glass Reinforced Polyester.  This description encompasses a broad range of products with varying levels of quality.  The FRL system is designed to be used with numerous surfaces including acrylic, gel coat, ABS, and other spa surfaces.  We can refer you to a contractor that has been qualified to perform these applications.

Thanks,

Rob

To Multi-Tech Products

Hello, I have a customer that needs to add more mechanical support under their spa to distribute the weight more uniformly, and reduce stress levels to prevent cracking.  It is out of the manufacturer’s warranty. What do you suggest?

Thanks,

Joe

To: Joe

The following picture shows a very nice aftermarket adjustable support added to an FRP Spa shell.

Feb 2015 download 016

The most important requirement for installing additional support is to prevent the new beam from puncturing the wall of the spa.  The method used to accomplish this is to install the beam so it transfers the weight to a strong metal plate between the beam and wall.  Please reference the picture above.

If there is a seat, step or flat area that would accept a support beam, and if it is accessible, remove any foam and expose the structure of the shell.

If you believe there is a plate and need to confirm, grind off the resin/glass to expose the plate for confirmation. The picture above shows an intended design and original equipment manufacturer (OEM) requirement. The plates were built-in at the factory at the time of manufacture. That is not going to be the case on every spa shell.

There is a wrong way to add support. One example is adding 2″ x 4″ wood stud material directly to the shell without a  plate.

IMG_0385

This is very bad practice since the large load of the spa will force the wood beam to eventually puncture the shell wall. I have seen this many times as a technician in the field. Even the nice support beam in the first picture above with its built-in,  top metal plate would pierce a normal spa wall without the addition of a strong weight distribution plate embedded in the structure or added in some alternative method.

Ideally, the best method would be a wood plate (as large as possible for the flat area). I would suggest a block of wood 2″ thick x 12″ x 12″ to start or as large as it can be while achieving good contact with the flat area. Be sure the plate sits flat against the spa structure.  Try to make it parallel to the spa base.  Use a 4″ x 4″ beam cut to size for the support. Be sure the 4″ x 4″ beam sits solidly on the deck, concrete pad or spa frame.  A plate may be necessary there as well.

IMG_0390

It would be best to secure the plate and support to the spa shell.   It should be done with Multi-Tech Products Polyester resin paste. Resin paste will provide about 30 to 40 minutes working time before it sets.  It is somewhat temperature dependent. In weather below 55 degrees, it may be necessary to apply heat after the application to cure the paste.

Grind the surface with 50-100 grit sandpaper to accept the Paste for good adhesion.

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Apply catalyzed paste to the plates prior to setting them in place.
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Secure the plate to the bottom of the spa with Resin Paste. Secure the beam to the bottom of the plate with the same “Paste”. The “Paste” can also be used to achieve maximum contact between the plate and the bottom surface of the spa structure where angle changes or uneven surfaces prevent full contact.  Good, wide area contact is needed to distribute the load.
IMG_0430

If the environment under the spa is frequently wet and the wood might eventually rot, use treated lumber, or the plate and the beam should be encased with resin and fiberglass prior to installing the beam and plate.  The following picture shows the wooden plate after encasing in fiberglass reinforced resin.

IMG_0447

 

 

 

 

 

 

If the spa needs to be lifted to insert the beam device, install the plate with paste, and allow it to set (cure).  Then lift the area up with a hydraulic jack (car jacks work, also).  Push the new beam into place (adjust beam length, if needed), retract the jack and allow the spa to set on the new beam.
IMG_0437

 

 

 

 

 

 

 

 

 

 

 

If additional supports are needed, repeat this process in order to distribute the total spa load throughout the spa.  One way to determine the need for additional support beams is to empty the spa, and put significant body weight in the unfilled spa shell.  If the shell moves, flexes, or the seats move downward with weight applied, this could indicate the need for additional under spa support.   This movement could would be due to either inadequate FRP reinforcement or insufficient mechanical support devices.  Properly distributed support is required to keep the spa shell from excessive downward movement due to the load derived from water and humans.  Pay close attention to the lip.  If a spa shell is built in a way to rely mostly on the edge support to provide the structure’s strength, the lip will move and deflect downward.  This would cause initial sagging and eventual cracking of the spa shell inner lip area.  Also, cracks inside the spa shell at upper corners could confirm inadequate supporting fixtures.  If the spa is within the manufacturers warranty, I would consult them before proceeding with an independent repair.  If it is not covered by warranty, good judgment must be used, but excessive movement begs for additional support to avoid problems.

Rob Clos

 

 

To: Multi-Tech Products

I am a spa surface repair contractor, and I perform manufacturer warranty work and non-warranty repairs. I have a customer with an acrylic spa containing a crack at the rim. What causes these type of problems, and what is correct method to repair?
Thanks,
Carlos
To: Carlos

Carlos, thanks for your inquiry. The information I am about to share will be very valuable to you, and other repair technicians. It will enhance your overall knowledge on troubleshooting spa problems, and improve your repair results. It will minimize the potential of returning at a later date to fix the same or additional cracks. This will make you a more valuable resource to your manufacturer clients for warranty repairs. We also recommend that you know your manufacturers well. That includes the basics of their designs, and the terms of their warranty.  Understand the manufacturer’s guidelines for installation.

If it is possible, make a visit to the manufacturer’s plant. During a complete tour, pay attention to what they use for shell support, and where it is placed. Ask about the use of insulating and structural polyurethane foam. Check the thickness of the shell in various locations. Observe if there are any unique materials or devices used to add reinforcement. One manufacturer uses large diameter PVC pipe to provide support under the key portions of the spa (picture below). Understand that a spa is a reinforced composite structure, and the details of the reinforcement are extremely important Some manufacturers even have specifications on how much deformation along the rim is allowable under normal loads.
Also, know what the shell material is. Is it monolithic acrylic, or is it co-extruded acrylic over ABS? Is it reinforced with FRP (polyester resin with chopped glass fibers), or is it polyurethane? Is a vinyl ester used in the reinforcement composite?

spa support

Your question is a very complex one. First, you did not mention whether it is a portable spa, or if it is an in-ground or in-deck installation. You also did not mention whether it is under warranty.  Also, if it is a portable spa, does it have an ABS plastic pan for a bottom?

Before repairing a cracked spa, a repair professional should investigate the circumstances enough to try to determine the root cause of the crack. This may not be easy, but you should strive to define the most logical cause. First, cracks occur when the material is subjected to a stress that exceeds its strength. The material strength will decline as temperature is increased. Certain types of chemicals will also accelerate crack formation. See other blog entries that discuss chemical attack. Acrylic is known as a fairly brittle polymer, and will crack under excessive stress. Obviously, a large impact from another object will cause a crack.

In the absence of an impact, most spa cracks occur due to inadequate structural reinforcement. An 8-ft. spa may contain 400 gallons of water, which results in about 3200 pounds of weight. Add a few people, and the total weight can exceed 4000 pounds. Unless the stress ( pounds per sq. ft.) from this weight is spread over the entire surface area, it can cause a crack(s) at the high-stress points. This is typically at the rim.

So, manufacturers of portable spas must incorporate enough support beams or other devices under the rim, seats, and floor to accomplish this stress reduction. Sometimes, manufacturers fail to accomplish it 100% of the time. The following picture shows one example where the weight actually caused the vertical support boards to bow under the weight. This magnitude of deflection is very likely to cause sagging and cracking of the rim.

IMG_0088

If you look behind the skirt of a portable spa, and see any evidence of deflection, you can conclude that additional support might be needed. Sometimes, you can determine this by checking how straight and level the top edge is. Portable spas should be placed on a concrete or other strong pad to facilitate the function of the supporting structure. If the spa has a strong ABS base, it enhances the overall performance, providing it has the required design.

In troubleshooting root causes, it is helpful to know that if the crack is separated, the area was in tension. If it is pushed together with a ridge, it was in compression.

Now, if the spa is in-ground or installed into a wooden deck, it falls to the installer to assure that ample support is included under the frame, rim, seats, and foot-well of the shell to distribute the weight around those load-bearing surface areas. A commonly used technique is to wash sand into the cavity between the shell and the excavated dirt.  It is important to provide support that limits deflection in all critical areas similar to the photo above showing the use of PVC pipe.  The rim area also needs to be supported.   The information above will apply to analyzing the cause of cracks in these type installations.

I have included some pictures showing some examples of cracks from over stress.

Crack 1Crack 2

photo 1

 

The cracks can be repaired by following Multi-Tech Products’ standard crack repair procedures as shown at the following link.

http://www.multitechproducts.com/content/Procedures/SPA-REPAIR-Quick-Glaze%20_revised-10252011.pdf

The spa shown in the next photo developed cracks at the rim.

photo 2

Please note the brick blocks it sits on.  Unless the spa has an ABS pan base or other type of rigid platform between the bricks and the spa bottom and constructed as a self-supporting unit, it would not comply with normal installation specifications from a manufacturer  Therefore, cracks would not be covered by a warranty.  Most portable spas are designed to set on a strong, steel reinforced concrete pad or a wood deck with correct spacing of deck joists, correct beam span, and proportionate post pillar spacing for strong deck construction.  A weak  or improperly supported deck would cause the same type of crack shown in these pictures.  This spa’s crack was at the center of one rim edge.  This suggests the spa is suspended at the rim with little support in the critical areas mentioned above.  Large spas (> 7ft.) are more likely to crack in this manner.  The following diagram shows one example of a well-designed deck.

Pad

A technician should inform the customer of these issues, and make a recommendation to correct the support issues.  If the customer chooses to ignore the advice but still wants the contractor to perform the repair, a warranty should not be provided.  Also, this example of a crack edge would require structure repair at the back of the shell before the cosmetic repair was performed.  Otherwise, new cracks would likely form in the future.  The best service is to fix all of the problem sources to prevent future call-backs, and an unhappy customer.

Thanks,
Ken Wolfe
Consulting Chemical Engineer

To: Multi-Tech Products

I own a spa service company, and I have a customer with a unique problem. He owns a large yacht, which had a spa installed several years ago.  It has been abused by failing to keep it covered when not being used. Also, it may have been exposed to the wrong water maintenance chemicals over the years. It is extremely faded, and has crazing and cracking in some areas of the acrylic surface. Since it is still functional, and would be expensive to remove and replace, the customer is inquiring if there is a simple way to renew the surface color and fix the cracks. He is asking about painting with a pool paint or Zolatone® to match the granite appearance. There are a lot of jets in the spa, and some would be very difficult to remove, if a spraying operation was required. What do you think?

Thanks,
Bill

IMG_3257

TO: Bill

I agree with you. The spa is crazed and cracked mainly due to over exposure to the sunlight (i.e. no cover in use).  Also, the use of strong water chemicals like Tri-Chlor was probably the major factor in the fading, although the excessive UV exposure contributed.  Acrylic sheet manufacturers have confirmed that Tri-Chlor will fade the pigments in acrylic spas and should be avoided for use in maintaining hot tub water chemistry.  Tri-Chlor is intended for use in swimming pools.
First, Zolatone® is a brand of hybrid lacquer paint, and will peel from a wet environment surface rather quickly.  This product, although speckled in color, is intended for top-side and non-wet areas in marine, auto, and industrial applications. It should not be used below a spa water-line, in tank or wet bilge areas. Even clear coated, Zolatone® will delaminate when painted onto constantly wet and high moisture environments.
So, a spa/hot tub refinish is out of the question. In fact, there is not a coating available that would provide a “quick” fix to renew a crazed/cracked acrylic hot tub surface long term. This even includes swimming pool and bathtub coatings, as well as marine finishes, and let’s not forget gel coat as paint. The reason is that the acrylic surface will continue to crack, craze, expand and contract under the applied painted coating. The cracks will simply come through, along with rapid delamination (peeling) of the coatings. These paints are just not made to withstand heated water, constant moisture exposure or chemicals.  These factors will cause  bubbling and peeling of the coating.  However, they do work well when the surface stays dry.  Moisture must dry quickly from these coatings in order to stay pristine, and adhered to the resurfaced substrate. They work well for resurfacing bathtubs. The tub is filled (gets wet), drains (dries) and the surface will continue adhered to the substrate.  Overuse, or a dripping shower head or fixture will result in constant wetness and the paint will fail.  Furthermore, pool coatings or marine anti-foul paints have an application life of only about 3 years. Therefore, these coatings would have a short life expectancy on a spa in a spa application.  Under spa conditions, we have seen these types of coatings fail within a few months from application.

Since there was no commercially available means to meet this need, we developed a process that works, and performs well under normal spa and wet conditions.  It is a special resin embedded with glass fiber reinforcement. The reinforcement along with the high performance resin adheres to the original spa structure, and creates a barrier surface with minimal expansion and contraction. The system is laid-up by hand and will give an expected life of 15 to 20 years. We developed this system specifically for spas, tanks and challenging wet areas as a economical method to extend their life.  It is our FiberGlass Reinforced Lining (FRL) system. It adds a new reinforced, white colored layer on top of the existing surface or prepared structure. You can see the system components and procedure at the following link. It is contained under the Technical tab in our website.
http://www.multitechproducts.com/content/Procedures/FRL%20PROCEDURE%20Final%20Draft.pdf

Your application doesn’t require removal of the jets or other fixtures, since the crazed areas on the subject spa do not appear to be causing severe peeling or delamination of the acrylic layer.  It would not be necessary to remove the acrylic or repair the areas before applying the FRL system.  The finished FRL layer will be about 1/8” thick, so it will contribute some additional strength.  In other words, it is a structural finish.  Since the FRL final color coat is white, it will provide an attractive textured finish and appearance that hides the underlying fiberglass throughout the FRL application.  It is easy to clean, and is resistant to fading by sunlight.    With proper water chemistry maintenance, it will retain its gloss.  It has proven to add long term life to spas in these high end settings where replacement was not an easy option.

I hope this helps. Our Customer Service Department will help you in ordering the proper kits and materials to do the job.

You can see the FRL components at:

http://multitechproducts.com/resin-fiberglass-resurfacing-kit

Thanks,
Rob Clos

TO: Multi-Tech Products

I am a spa dealer with a customer that has reported a problem on the surface of his acrylic spa. The attached photos show marks appearing on acrylic shell surface. They were in the area around the filter canister, and looked small stone chips that you get on the front end of an automobile. The customer is one off our best on chemical management and takes great care throughout the year to service his tub.

Can you take a look at the pictures and give me your thoughts on the potential cause?  I have never seen this type of issue on a shell. It’s within about a 12″ area within the filter housing but doesn’t seem to be anywhere else.  Could it involve a previous surface repair?

Thanks,

Tony

 

To: Tony

The pictures indicate that this is another example of acrylic pigment fading and/or topical blistering due to exposure to a strong sanitizing agent (oxidizer).  Although rare, we have seen several similar examples over the years.  One acrylic manufacturer has even been able to duplicate this phenomena in the lab using “Tri-Chlor” tablets.  Someone has created this problem with pool chemicals either by using the wrong chemical, or using too much of an approved chemical. The appearance is consistent with what we have experienced with Tri-Chlor.

P1070189

The logical mechanism of your example is that a very strong oxidizing chemical (probably in solid form) sunk into the water, fell down the vertical surface creating surface damage as it sunk into the bottom of the foot well or seat.
Acrylic is by far the best material for spa construction, and withstands many harsh conditions, but it is not perfect.
Although this type of damage is rare, it suggests that the industry should increase it’s communications on chemicals to avoid, and how to use the recommended ones.  There is evidence of extreme chemical dispersion into the filter housing, and it reached a very high localized concentration.

From my observations from the photos, I see:

P1070343
1. A peeling effect of acrylic. This could happen where a tablet would set for a period of time in one spot on the acrylic.

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2. A scratching effect. This can be where a large round tablet would float and roll around creating damage to the surface. Or the scraping of chemical damaged or repaired acrylic.

P1070198
3. Rust in the affected areas. This would be from iron in the water reacting with the oxidizer, and depositing on the porous surface created from the chemical damage.

P1070191
4. Attack on the silicone in this area also suggests the presence of strong chemicals in the same area.

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5. Bleaching of the black filter fixture is an additional indication of chemical oxidation.

If there is a repair in this area, the peeling would be of a clear coat. However, the same chemical damage, described above, most likely would have caused the damage to the repair.  A pre-existing repair could only be determined by inspection by a repair pro that has experience with chemical damage.

The good news is that it can be removed by sanding through the oxidized layer (chemical damage) down to good acrylic.  Then it can be buffed and polished to a higher gloss. It will depend on how thick the oxidized layer is, which depends on how long the acrylic surface was exposed to the high concentration of oxidizing chemicals.  Hopefully, the discoloration is only “skin” deep. From my experience, it looks like it is less than a 1/16″ (1.6mm) deep.

The colors could change as you sand, and become darker or lighter.  It would be unpredictable based on the pigment mixing through the sheet. That should not be a big problem since it is in the filter area where it is hidden from view.   The gloss would be maintained through the proper buffing and polishing process.  If there is a repair, you should find a light-colored filler under the repair coating.  In this case, depending on the repair filler depth, it would need repair including a new coating and clear coat for protection. It could have been a surface repair that just covered up a light surface issue, and may buff and polish out to a normal appearance as well.

Here are other examples of the chemical issues and more explanations of causes. Follow the links in the articles to the proper remedies:
https://multitechproducts.wordpress.com/2014/12/15/surface-discoloration-in-an-acrylic-spa/
AND
https://multitechproducts.wordpress.com/2014/11/04/282/

To repair the surface, sand with a progression of 220, 320, 400 grit sandpaper. Finish with 600 grit wet/dry sandpaper. Then to recover the gloss, buff using a high-speed (variable to 2500rpms) with a good quality buffing pad and medium grit buffing compound.
We have a video demonstrating the entire procedure, and it can be down loaded.

http://www.multitechproducts.com/buffing-and-polishing-dvd/

Thanks,

Rob Clos

Jeff Enswieler 4

We are occasionally asked what has caused a localized discoloration in a spa.  Most of the time, this change in color appears as a bleached surface.  There have even been examples where tiny blisters were present in the bleached area   In every case we have investigated, the root cause has been localized exposure to a strong sanitizing chemical.

The majority of spas are produced from  a  cross-linked, high molecular weight acrylic polymer sheet, a material that is very resistant to chemicals.  However, no product is perfect when it involves chemical resistance.   Spas require the use of sanitizing chemicals to maintain water chemistry.   Manufacturers provide recommendations on what products to use, and how to use them.  Failure to comply with these recommendations can lead to problems.  Even if a product might be used in a swimming pool, it may have issues when used in a spa.

Pure acrylic is clear with transparency better than most glass.  Pigments are added to the liquid acrylic to create the attractive colors and effects.  New colors often use exotic pigments.  Sanitizers for water are oxidizing agents used to kill bacteria, algae, etc.  Some are stronger than others.  The most common spa sanitizers are compounds of chlorine or bromine.   Some of these products have been found to bleach the acrylic pigments, and cause discoloration.  Manufacturers recommendations are always designed to prevent concentrated chemicals from long contact with the acrylic surface, and the plumbing system.  Water treatment chemicals for spas are best when in liquid form since they are easier to control concentration.  All examples of spa surface discoloration, that have been reported to MTP, have been caused by  one of these water treatment products.

Inorganic chlorine compounds such as calcium hypochlorite and sodium hypochlorite  commonly used sanitizers for swimming pools and spas.  However, they are both effected by sunlight, so they require the addition of cyanuric acid to stabilize the chlorine in outdoor pools and spas.  Organic chlorine compounds are products combined with cyanuric acid. Sodium dichlorostriazinetrione (“dichlor’) and trichloro-s-triazinetri-one (‘trichlor) are both popular stabilized chlorines for water treatment of outdoor pools.  Most of the spa discoloration cases we have seen have been the result of the use of “tri-chlor”.  Specifically, they have been due to the use of this chemical in the form of solid tablet.  This product dissolves slowly in water, and is a very strong oxidizer as well as increases the acidity of the water.  When these tablets are in contact or close proximity to the acrylic surface, it will attack the acrylic pigments and cause bleaching, and sometimes blistering.  Di-Chlor is a weaker chemical, and should be the stabilizer of choice for spas and is available in granular form.  Furthermore, when any sanitizer or acid is added to spa water, the circulating pump and jets should be running to assure rapid mixing of the chemical into the water.  This avoids creating localized regions of highly concentrated chemicals.

These problems have been verified by one of the acrylic sheet manufacturers.  They performed extensive testing of several water treatment products, and found that ‘trichlor” tablets can cause the bleaching similar to the examples that we have  observed and have been reported to us. They also found that when combined with hot water, it would cause blistering.  Some cases reported to MTP showed a red, rust-like material in the bleached area.  Their tests duplicated this phenomena when there was a source of iron in the water.   High concentration of the oxidizing chemical is a prerequisite for the discoloration.  This is facilitated by tablet form chemicals, since they can lay on the acrylic surface while dissolving.  If water is not being circulated, there will be a very high concentration at the interface of the acrylic and the tablet.

chem bleach1chem bleach

The two photos above show discoloration and blistering from the incorrect use of chemicals like “tri-chlor”.

Some people like to use floaters with a chemical inside.  Although it is a convenient way to treat water, it is not recommended, since it can cause problems.  The floater can rest against the side of the spa, and since it is in close proximity, it can cause bleaching of the surface.

Poor chemical control can also cause problems within the plumbing system by reacting with sealants, o-rings, etc.  There have  been reports of other spa components being compromised the use of bromine sanitizers, and ozonators (direct ozone addition).   Any chemical should be quickly dissolved and diluted with water to avoid problems.   It is very important for a spa owner to maintain total water chemistry (e.g. pH, chlorine, total solids, etc) as recommended by the manufacturer.  Various problems can occur if chemistry gets out of control.  For example, if chlorine level is too high the vapors  can bleach the under surface of a spa cover.   Excessive chemicals in water can also damage the jets, controls and fixtures.  Check with your manufacturer for their recommendations on how to maintain water chemistry in your spa.

Sometimes, the bleached surface can be removed by sanding and re-polishing, so surface appearance can be recovered.  However,  avoid repeating the factors which caused the original discoloration.

Following are some photos that provide examples to chemical bleaching (chemical burns).  The owner of at least one of these samples reported seeing pits in the bleached area.   There are chemicals that have been known to attack cross-linked acrylic.  One example is Wintergreen oil.  Although, the normal mode of failure from chemical attack on an acrylic surface is stress cracking, failure can occur in various ways.  Failure in a spa caused by wintergreen oil have been seen where it looked like a liquid had been poured on the surface , and it ran down the side.  The acrylic was discolored, and microscopic crazing was present.  Refer to information on stress-cracking in the website, http://www.multitechproducts.com.   So, unless a chemical has been approved for use in a spa, avoid using it.

The pictures above illustrate these problems in solid color and marble (multiple colored patterns) color spas.

The apparent defect can also occur in “granite” spas as shown below.    Again, they can be repaired using a sanding procedure.  You would start by using 80 or 100 grit sandpaper until the discolored area is removed, and you see the original color.  Then you would finish by using 320 grit wet/dry paper, and finally 400 grit.  If granite texture needs to be regained, you can use Multi-Tech Products K2000 clear topcoat with a brush.  Use the procedure provided to add texture.

Granite discolor

 

 

 

 

 

 

 

 

The picture below gives an example of the worst case of chemical attack we have seen on an acrylic spa.  This severe, widespread discoloration would not lend itself to sanding, buffing, and polishing to recover the original color(s).  Read the message at the link for more information on cause and refinish options on this case.

https://multitechproducts.wordpress.com/2013/11/04/282/

bilo-pic

 

 

 

 

 

Some general information on chemicals used for spas follows:

Calcium hypochlorite is available in granular or tablet form. It provides 65% available chlorine by weight and remains stable if stored in a dry, cool area. The chemical can be dissolved and introduced as a liquid, or it can be added in dry form. When
applied directly, it may cause a temporary cloudiness. Direct applications should be broadcast evenly over the water surface to avoid bleaching.
This chemical, when contaminated by or mixed with an organic compound, can produce a fire. A good rule is never to mix calcium hypochlorite with another chemical or store it in anything but the original container. Mix the chemical into water not water into the chemical. Calcium hypochlorite should not be handled with bare hands and must bekept off the operator’s clothes. As a chlorinating agent, calcium hypochlorite will slightly increase water pH. It’s pH is 11.8.

Sodium dichloro-s-triazinetrione and trichloro-s-tria zinetrione – chlorine compounds that contain cyanuric acid, and are used to stabilize chlorine.  The dichlor is more soluble and provides 56% or 62% available chlorine, depending on formulation.   The dichlor compound has little effect on pH, while trichlor is extremely acid (pH 2.8 -3.0).  Dichlor can be added directly to the water. The major effect of cyanuric acid on hypochlorous acid (HOCI) is to keep it from being decomposed by ultraviolet light contained in sunlight. Because it is readily decomposed by LTV light, the dosage of a chlorinating agent loke calcium hypochlorite that is sufficient for an indoor pool/spa is dissipated rapidly in an outdoor pool/spa.  Cyanuric acid bonds with the available chlorine in a manner that does not use up the chlorine.  At high stabilizer levels (over 100 ppm), chlorine’s efficiency may be reduced. The operator should consult the local codes and manufacturers’ recommendations on the proper use of stabilizers.

Regards,

Ken Wolfe (Chemical Engineer & Consultant)

To:  Multi-Tech Products

I am a spa dealer in Arizona, and I have a customer asking about extreme color fading in their 15 years-old, in-ground acrylic spa.  I have attached a photo.  What would cause this to occur?  Would spa chemicals be a likely culprit?  Please help.

Thanks,

Kevin

bilo pic

     (click to enlarge)

To Kevin,

Yes, your photo confirms a problem with extreme color fading.   There are two common causes of fading in an acrylic spa.  Pure acrylic is transparent, so pigments are added to achieve the attractive colors and effects.  These pigments are subject to fading from over exposure to chemicals and to a lesser degree sunlight  For example, it has been proven that high concentrations of chemicals like “tri-chlor” can completely bleach out spa surfaces.  UV light from the sun can also be a contributing factor.   Your spa may be suffering from a combination of both problems.  The cracks around the top edge are evidence of excessive exposure to the sun’s heat.  The sun’s radiant energy can result in very high acrylic surface temperatures during the day.  The cracks form as a result of repeated expansion and contraction from large swings in temperature from daylight to night.   This occurs frequently when a cover is not used when the spa is not in use.  If you look closely, the entire top surface is covered with cracks and crazing.  See our crazing blog entry below.   Manufacturers insist on  the use of a cover when the spa is not in use.  This is required to prevent cracks and crazing.  Most manufacturers will void a warranty when a spa cover is not used routinely.   See the “Why use a Spa Cover blog entry”.   It describes more on crazing.

https://multitechproducts.wordpress.com/2013/08/14/why-use-a-spa-cover/

Fading like your example would require years of exposure to strong sunlight, therefore, I believe excess sanitizing chemicals in the water is the prime cause of the fading.  Your case is the worst example of chemical/sunlight fading that I have personally seen in my 25 years’ experience.  You should also read the following blog entry.

Additional information at:   https://multitechproducts.wordpress.com/2012/04/20/surface-discoloration-in-an-acrylic-spa/

Early fading is usually limited to a thin layer on the surface.  In these cases it can be removed by sanding, buffing, and polishing the surface.  However, eliminate the source(s) of the problem.  Refer to our procedures in the website, or our Buffing and Polishing DVD for instructions on renewing the gloss on the surface.

https://multitechproducts.wordpress.com/2012/04/14/how-to-buff-and-polish-spa-surface/

You asked about chemicals used to maintain water chemistry.  Since they are strong oxidizing agents, it is a logical question.  First, if these chemicals are used properly, there will be no issue.  Some exceptionally strong oxidizers can create problems.  For example, it has been shown that high concentrations of “tri-chlor” in hot water can cause severe bleaching in acrylic spa surfaces.   Spa owners who use this chemical in the tablet form have real problems with fading, since they can rest on the acrylic surface, and dissolve slowly.  A high concentration of the chemical exists at the immediate area surrounding the tablet. When chemicals are involved, the fading is generally at the water line.  Generally speaking, we have witnessed very few issues with acrylic due to any of the common spa chemicals, which include bromine, chlorine, and ozone.  Acrylic is an outstanding product for spas, and has fewer problems than any material ever used for them.  But your photo shows what can happen when the spa is abused, and manufacturer recommendations are ignored.

I hope this helps.

Regards,

Rob

To Multi-Tech Products Corp.

Thanks for the great advice on this spa.  However, do you think it can be salvaged?

Kevin

To: Kevin

The simple answer is that it is possible to salvage.   We offer a FRL system that can be used to refinish  and create a completely new, attractive, long term surface that will last 15 to 20 years.  For information and instructions, go to http://www.multitechproducts.com/categories/frl-refinishing-system/

Also, refer to http://www.multitechproducts.com/content/procedures/frl%20PROCEDURE%20Final%20Draft.pdf

Your spa is a good candidate for the FRL resurfacing system, which is designed to create a new attractive surface on an aged spa that still is structurally sound, or is installed in a location that would be very expensive if one were to attempt to remove and replace it.  Even if there are structural issues, reinforcement can be added prior to the FRL application.  The FRL materials are applied directly on top of the acrylic surface.  Do not try this with bathtub, marine, or pool refinish coatings, since they will only provide a few years of service before peeling or delaminating from the surface.  Our FRL system has been proven to work in this application,and even over severely crazed acrylic, and is perfect for oxidized gelcoat surfaces.   However, it should only be performed by trained surface repair professionals, but we have seen people with handyman skills be successful with the process.  One important consideration is that the mechanical and electronic systems for hydrotherapy are still functional, and without issues.  Some of the advantages offered by the FRL system  include:

In ground spas may require a lot of costly work to remove and replace.  The FRL system will save dollars, and is a permanent solution.  The spa can be in service again in about one week.  Most structural problems can be fixed during the process.  Even modifications can be added to the steps, seats, and tile areas using standard composite methods prior to the FRL application

Please let us know if we can be of further help.

Good Luck,

Rob

To:  Multi-Tech Products

I want to thank you for your assistance in supplying a great system and help to replace and renew part of the surface of a swim spa installed in a home in Alaska.  The spa was originally produced from a co-extruded polymeric sheet with fiberglass reinforced resin for mechanical support.  Due to the presence of un-cured resin in the support structure, blisters had occurred around the bottom of the spa.  They were too numerous and widespread to repair with your standard procedure.  Furthermore, as the picture below shows, it would have been very expensive to remove and replace the entire spa   You can also see a photo showing some of the blisters..

IMG_3336.IMG950658

These blisters were located only around the lower portion of the spa, so your procedure for renewing a portion of a spa surface was ideal for this job.  As your procedures state, we created a line of demarcation establishing the boundary of the material to be removed and replaced.  Then we stripped this top layer from the spa with  the aid of a chisel and hammer.  We removed the entire bottom  of the spa.   Then we applied new fiberglass mat and resin using your FRL Kit to the affected surface.   See photos.

IMG_0684 IMG_0681IMG_0697

Padres Spa Pictures 223

 

We completed the job following your recommendations using the products in your kit.  The following photo shows the final result.  The home owner was ecstatic about the appearance, and our ability to repair it without the demolition of replacing the entire spa.

IMG_2098

Thanks again,

Jeff

To:  Jeff

I want to thank you for your testimonial on our FRL (Fiberglass Reinforced Lining) System.  It was designed especially for this application, and we have had many satisfied customers including the San Diego Padres baseball team where the spa in their locker room was renewed.  We also want to thank you for trusting and using all of our products to repair spas and bathtubs made from acrylics, gelcoat, and other materials.

Regards,

Rob Clos

President