🚀 go-pugleaf

In message <7uvzn56lm1p.fsf@gina.research.nokia.com>, MB <*@*.*> writes
>Chris Townsend >
>> I think we're talking about relative amounts here. I know there is
>> some heat loss due to radiation, I just don't think it's very
>> significant compared with the other types of heat loss.
>
>It'd be very interesting to see some figures, but I agree,
>it can't be that big. Otoh, the cost of reducing the radiative
>heat loss by making, say, a down jacket in white rather
>than black is zero.

The cost is only zero if the white fabric is the same price as the 
black, which it may not be if it's non-standard. Many specialist makers 
only use small amounts of material. They buy the colours and shades 
available.

> An alu coating would add cost and some
>weight (impairs breathability?), but would weight-wise
>most probably be worthwile [Randall].

I've tried garments with alu layers inside and they do impair 
breathability. Alu on the outside would make for a highly visible 
garment,
>
>> Various Swedish companies like Fjallraven used to make tents with
>> silver flysheets to keep out the sun during the long hours of northern
>> summers. I didn't find when I tried one that it was noticeably cooler
>> than non silver tents. (It was much darker - you needed a flashlight
>> at midday). The coolest tents I've used were cotton ones (with bright
>> orange flysheets).
>
>I'm a bit surprized, as I would have expected that they'd be
>markedly cooler in hot sunshine. Just like the shiny tarp
>works in the desert? But, I never tried a silver Pop-out, nor
>have I been hiking in desert.

I haven't used a tent with a silver flysheet in very hot temperatures 
(probably no higher than 20-25C). I did find tents with such flysheets 
hot and stuffy inside.
>
>A big advantage with the shiny alu-coating is that it also
>blocks UV. Stephenson continues to offer their tents with
>aluminized flies, but at a substantial surcharge.
>
>At least latter Fj�llr�vens with silver-coloured flies had
>the lower parts of the flies in some ordinary colour that
>wouldn't block light so badly. For the same reason Stephenson
>recommends choosing a light-coloured fabric for the ends of
>their tunnels.

The one I tried was a Fjallraven with a complete silver flysheet. This 
was back in the 80s.