I simply used my hand as a heat source to find how much loss there was you have been suggesting that you will see a 30ºF loss to the tub wall I am suggesting that one or two degrees is all that will be lost. My hand being 94.5ºF and the measured transfer though the tub wall was 92.6 that is a loss of 1.9ºF. That is in a room temp of 72ºF and the start temp of the plastic was that same 72ºF

You are stating that a pad producing temps in excess of 130º to 160º will magically drop to 94º with just the thickness of 1mm plastic tub wall. I have just proved that 94 becomes 92 that is so far away from the 36+º shift you are suggesting. If you were correct I should have not have seen ANY change or at least very little (73 maybe???) in the temp of the tub when heat was applied.

I agree that plastic is slightly higher than glass in an equal thickness (depending on the plastic type I am skeptical of PP would be) but tanks are MUCH thicker than plastic tubs!!!! Where oh where did you get 6mm thick tubs? I would love to get some!!!

You have constantly compared one situation to something so totally different that it is silly. A tub is not the same or even approaching the same R value of a tank. Do you actually believe 1/32 inch plastic has higher insulation value than 1/4 inch glass? That is silly!!!

This whole test of yours is so laughable I don't know why I am bothering I know the answer before any test need be done. Tubs transfer heat fairly well, how you can suggest this is not true I simply cannot understand. Unless you mean bath tubs? You have compared plate glass to injection plastic and claimed injection plastic insulates better... why not injection plastic to cast iron it is just as logical.