Re: Density
<1.2 kilos / (50cm *40cm * 15 cm) = .04g/cm^3.
(based on numbers in this article)
for reference, water's density is 1.00g/cm^3 and aluminum's is 2.70 g/cm^3.
Wow, that's not as dense as I was expecting. For comparison, the styrofoam we use on a dryviit system for buildings is .016g/cm^3 so the foam on the external tank was a little more than twice as dense.
My source is the Dryvit cut sheet on my desk, for those interested in sources :)
-Steve G.