Hello David, I use an exterior deicing heat cable. The exterior puts out more btu s to overcome the mass of the tub. Since it's gfrc, I lay the wire in between back coats. The electrician wires a timer to the cold lead, That way the customer sets the timer for 20- 30 minutes before filling the tub. Hope that answers some of your questions.
well I had it made out of foam,then formed the foam by sanding it . I put a selfleveling epoxie on the foam to strengthen it and to fill the voids.Wet sanded it then put a epoxie primer that auto body guys use.once the primer was applied i guide coated it to show me flaws,wet sanded that.Put a primer, sanded that at 1500 to make it look like glass and really smooth.I use alot of what auto guys use on most of my forms.If you use bondo for seems,there is this stuff called icing.Its a selfleveling bondo easy to use,all i do is apply and sande it with 600 wet and dry paper by 3m.
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