This is an FYI to all readers looking for a way to further insulate existing interior, exterior walls, pipes, masonary, etc... I discovered this product, "Nansulate", while surfing and surfing the web for insulation ideas. I bought one gallon of the product and tried it on part of our exterior aluminum siding, part of the interior wall oposite this siding,and on an interior wall(which always feels cold) on the other side of the house. The product I tried was the "clear" which does dry absolutely clear, inside and out--as long as you follow the instructions(which are easy). After 24 hours, didn't notice too much change. After 48 hours, really did notice that the part of the wall I painted with the product was noticebaly warmer than the part NOT painted. You have to apply 3 coats or more to get the maximum results. I only have 2 coats on at this time!
SO, from what I've seen so far with 2 coats, there really is something to this product! There is even a type made just for metallic surfaces and many people coat their hot water heater and/or pipes with this product. Can only speak from my own experience. Read their web page. Nansulate.com