NA - Hot tub repair.. what resin?

MuseChaser

MuseChaser

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MuseChaser
Ok...I broke the internet today and don't know where else to turn although I've sent an inquiry to the folks at West System...

Our ancient, huge 8 person indoor built-in Jacuzzi-branded hot tub had two huge blisters in it. I ground them out today and have them drying out. Was planning on using cloth and West 105 resin, tinted close enough, tomorrow to do the repair work, but became unsure as to whether or not it's the best choice for underwater and constant exposure to bromine and occasional temps up to 105F. I've searched for hours, but can't find anything specific...just lots of "buy our hot tub repair kit" type sites without any specific discussion of resin types. I've done some extensive work in our sailboat using West 105 epoxy and various fillers, two part epoxy primers and paints, but no experience with polyester or acrylic resins. I have a suspicion that acrylic resin would be a better choice, but Amazon only shows clear craft epoxy using "acrylic resin" as a search. Is that acrylic?

More concerned with function than the aesthetics of the repair...just want to get the thing up and running again for some apres-xcountry/snowshoe-soaking of not-so-young-anymore bodies this winter.

Thanks in advance for any tips. Hopefully, one of you guys or gals is the expert I'm looking for...
 
What was the original layup?
 
IMG_20201012_165037872_1.jpg
Tom-D said:
What was the original layup?
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I'm really not sure. Most high end spas are acrylic now, but this one is circa 1984. It's a solid glossy brown in color (no swirls or metallic flake like you see in most modern tubs), and the color is through most of the layup. The layup is about 1/16" thick, over a rigid stranded fiberglass-looking insulation core.

Can post pics tomorrow if that would be helpful.

Edit..here's one prior to grinding out the blisters. One of them is visible in the pic...
 
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Personally, I don’t care for West System. I haven’t had good luck with having it cure consistently. But it is an epoxy resin, which is good. As a general rule of thumb, when you don’t know what the original resin that was used was, you’re best off using epoxy because it will stick to most resins.

If I were to guess, I’d bet the original layup was made with polyester resin given the age of the part. I don’t think epoxy was real common that long ago.
 
Do you have a model type? The owners manual for an Aero Select model I found says it was polyester resin, so if you can get the specific model, that might point you at the correct place.

If you have the original manual, check in the “cleaning” section.
 
Yes, use epoxy.
The only downside can be UV exposure if it's in direct sunlight after a couple years not going to like it so make sure you put a solid color over the top of it somehow.
Epoxy is the first then vinyl Ester resin then polyester resin . problem with the resin is they shrink . Epoxy has the best water permeation issues and adhesion.

Sent from my SM-G960U using Tapatalk
 
Thank you, everyone! Points regarding adhesion, impermeability to water, and susceptibility to UV damage taken and understood. What about resistance to damage from bromine? Any specific issues with 105 deg F heated water?
 
Two more pics, in case they're of any use. One shows a piece of the shell, the other a ground out area. Thanks again for the ideas...

IMG_20201014_074936672_1.jpg IMG_20201014_074949745_1.jpg
 
Capt. Geoffrey Thorpe said:
I've gone through gallons of the stuff - never had that problem.
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That’s what everyone says when I tell them about the problems I had. I’ve done a fair amount of fiberglass and carbon fiber work and have never experienced the problems I had with West System with any other epoxy or polyester resin I’ve used. A friend with composite experience was bound to prove me wrong about West System too, thinking that I kept mixing it wrong or something. He had problems as well. One time it worked fine and the next time it wouldn’t.

Since that time I’ve stuck to buying my resin from Composite Envisions or Fibreglast. Haven’t had any trouble with their products.
 
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mondtster said:
That’s what everyone says when I tell them about the problems I had. I’ve done a fair amount of fiberglass and carbon fiber work and have never experienced the problems I had with West System with any other epoxy or polyester resin I’ve used. A friend with composite experience was bound to prove me wrong about West System too, thinking that I kept mixing it wrong or something. He had problems as well. One time it worked fine and the next time it wouldn’t.

Since that time I’ve stuck to buying my resin from Composite Envisions or Finreglast. Haven’t had any trouble with their products.
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The only resins I've used so far have been West and TotalBoat. Both have given great results, with TotalBoat stuff being more budget friendly. The only times I've had frustratingly long total cure times, meaning sometimes as long as a day or two, have been when doing very thin painted-on coats with either. For layups, they've both been fine.
 
ester resins will adhere to one an other, as will the epoxys. the general rule is, if you can heat it, you can re-form it.
 
West responded and recommended their G/flex-650 resin, for better adhesion and flexibility in a thin layer, although they didn't address my questions re/ spa heat and bromine. Perhaps I'm overthinking that?
 
As for bromine, you’re actually talking mostly about bromide salts. Bromide, chloride, shouldn’t matter. If it’s good for saltwater boats, should be good to go.
-Holiday Inn Express chemist.
 
MuseChaser said:
View attachment 91025
I'm really not sure. Most high end spas are acrylic now, but this one is circa 1984. It's a solid glossy brown in color (no swirls or metallic flake like you see in most modern tubs), and the color is through most of the layup.
Click to expand...
Nothing to add here other than I'm a little disappointed that there's not even one message in this thread relating to a "hot tub time machine" joke.
 
455 Bravo Uniform said:
As for bromine, you’re actually talking mostly about bromide salts. Bromide, chloride, shouldn’t matter. If it’s good for saltwater boats, should be good to go.
-Holiday Inn Express chemist.
Click to expand...
Hypobromite is more correct.
 
Interlux Watertite Epoxy filler is my main go to filler for boat blisters.
 
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