Spa shell – Is it important?

Spa VacuumeThe spa or swim spa shell is probably one of the most important things to look at when it comes to buying a spa.

Why? Well think about it, the shell must endure the outside tempretures from below 0 to over 40 degrees celcius, At the same time the tempreture of the water will more than likely be the opposite so in winter it may be 2 Degrees outside and the spa pools tempreture may be set at 39 Degrees.This puts a heap of stress on the shell and all to often poor quality spas will only last a year or 2 before you have a major issue with the shell.
Why I say its the most important was that if you have an issue with your pump or electrical this is easy to access and replace, HOWEVER if you have a shell that bubbles or cracks, then throw away the spa!

All too often to the everyday consumer ALL spas look the same, but here are some points to consider: Some companies have made spas with fibreglass shells and this is significantly cheaper than Acrylic shells however they will not last with high water temperatures and so is an absolute waste of money. What you are looking for is an Acrylic Spa Shell.

Acrylic Spa Shell: Are all Acrylics Equal?
As with most things in life there are Great Acrylics and then there is just average acrylics. The 2 most noted brands come out from the US and they are LUCITE acrylic and ARISTECH acrylic. However even if you have one of these acrylics it doesn’t guarantee you that you have a strong spa shell that will stand the test of elements and time.

Vacuum Forming: The acrylic sheet are put into an oven and heated to a controlled temperature – The heated acrylic shell is then put over the spa mould and then vacuum formed to the shape of the spa. Only the BEST factories use a ZONE controlled oven which means different sections of the acrylic is heated to different temperatures so that the THICKEST acrylic shell is formed EVENLY.

Fiber Glassing: Since Acrylic is naturally porous a thin layer of pure Vinyl ester resin is sprayed onto the acrylic shell. This forms a chemically bonded undercoat. SOME COMPANIES STOP HERE
The better Spa Shells then have a layer of Marine Grade Polyester resin sprayed over the vinyl ester resin. Once this is applied it should be hand rolled to ELIMINATE any air pockets.

IMPORTANT – Only the Very Best Spa Companies Do this – The Shell is Cured in a temperature and humidity controlled oven. This step is SKIPPED by most manufactures just because of the expense of these ovens. However this is a VITAL GUARANTEE to perfect adhesion.

Only the Top Spa Manufactures then put a Final layer on the cured shell of GP resin mixed with stone powder and this gives the shell extra Rigidity. The final layer is then hand rolled to remove any air pockets.

As you can see that there is so much to a shell than meets the eye. One of the most common things I have seen is spa shells that bubble up after 6-12 months of use. This is because there was moisture trapped in between the Acrylic and fiber glassing and on a warm day it just pops the shell – Countless of people have been victims to this. Having the shell passed thru an oven and cured eliminates any moisture and guarantees you wont have this issue in the future.
Please remember the spa industry has allot of commission based cowboys so if you ask them direct do you cure your shells in an oven the Majority will say yes. Well then it wouldn’t be hard for them to show you proof correct? Please always ask for hard facts because 12 months down the track when you have a bubbled shell the sales guy will say “I didn’t Say That” and then your stuck.
Any Questions or feedback feel free to post a comment below.

3 Comments/Reviews

  • Kylie says:

    We recently purchased a Swim Spa and it has cracks in the acrylic shell.

    The manufacturer has offered to repair the cracks, however we are concerned that we will have problems with the spa in the future.

    Based on your above article it would seem that we should ask for a refund or replacement.

    However we are having trouble finding someone to confirm the quality of the shell and structure of the spa. Can you recommend someone who could help us?

    • Admin says:

      To help you I just need a little more info.

      Where and when did you purchase the swim spa?

      What suburb are you located in?

      • Kylie says:

        Thanks for your reply.

        We purchased the Swim Spa on the Mornington Peninsula in September last year.

        We are located in Mount Eliza, Victoria.

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