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There are three major acrylic companies...The acrylic has less to do with it than the bonding agent and sheer strength of the shell. The "friend" spaman is talking about is me... the spa was a D1 Amore Bay and it blistered pretty rapidly with just a small portion of it sticking out in the sun. I've yet to see the results with the new Cal's but my guess is this was a good testament right here!
Honest question here. Wasn't the blistering of the D1 shell due to the spa retaining the heat because of the full foam insulation? I don't think any full foam spas allow you to leave the spa in the direct sunlight without a cover or water. Non-full foam spas allow the heat on the shell to dissipate so they won't blister as quickly. That is what I've always been told. Let me know if that is incorrect.
When I had my Cal Spa torn apart due to freeze damage the place that had the least amount of foam was right under the main foot well just, I bet there was under 1" of foam under it. Let me see if I have a picture to show what I mean...Here we go, you can kinda see what I mean, right under the 2x4 that goes threw the middle
They are massive, man. One is the size of 2 or 3 softballs. I will post pics tomorrow I guess.