Tag Archive: Acrylic Spa


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

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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

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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.

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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.

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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.
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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.

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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.
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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 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

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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 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..

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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.

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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.

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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

Fixing a crack at a spa jet

To:  Multi-Tech Products

My spa has a crack at one of the jets, and water is leaking through. Will your acrylic granite repair  kit permanently seal the crack?  How can I remove the jet to make the repair?  It seems to be anchored very tightly.

Thanks,

Dennis

Jet Crack

 

 

 

 

 

To: Dennis

Obviously, you have a crack in the acrylic surface, and you report your spa has evidence of water leaking into the rear area of the shell.  Although it might be possible for the two events to be related, generally they are not.    The reason that most cracks in the acrylic surface do not lead to a water leak is that spa shells are constructed using at least two layers of different materials.  The acrylic surface is only used to provide the attractive color and effects.  This outer shell is produced from an acrylic sheet that is heated and formed (stretched) by vacuum into a mold.  The original sheet is only about .125″ thick, so there are areas in the bottom where the acrylic thickness is between 0.020″ and .030″ thick.  So most spas are sprayed with a polyester resin filled with chopped fiberglass strands (FRP) to provide the strength required for the shell.   Also, most manufacturers then spray a coating of a high density polyurethane foam on top of the FRP for insulation.  The FRP reinforcement is very strong, and it is adhered to the back of the acrylic.  It would be very unusual for this FRP structure to crack, which would be necessary to lead to a water leak.  Although the acrylic surface of spas are known to crack for various reasons, water is still contained by the FRP structure.  If you can actually see water leaking behind the crack, it would be one of those one in a million situations.  However, since there is a hole in the shell at the jet, it might be possible for the water to find a path through that hole.  Typically, silicone sealants are used to prevent leaks at the jets.

The most common source of water leaks is the plumbing.  These leaks are often difficult to find due to the insulation in the spa cavity, especially when the cavity is completely filled with polyurethane foam.  You may need to get a spa maintenance expert to locate and repair a leak in the plumbing.

However, to answer your question about the acrylic repair, our granite repair kits are designed for this purpose.  Please refer to our website, http://www.multitechproducts.com/pages/Procedures.html, for a description of the materials and procedure for the repair.  The granite repair kit will repair the crack up to the jet, and without removing the jet.   If the jet needs to be removed, you need to consult with a spa mechanical repair contractor or the manufacturer.

I hope this will answer your questions.

Rob Clos