Bushwalk Australia

Just wondering if this would work, mix it in with goose down, not sure what ratio of mylar to goose down you would need, my goal is a light warm bag.

Is my Idea insane

Cheers.

If you want warmth and light weight, why not just stick to goose down?

Sheet mylar could be an idea to reflect heat lost by radiation.

As for use as thermal insulation, i suspect the air pockets formed are too big and allow air to flow too easily for it to work well as an insulator on a small scale.

How about confetti Mylar

I am not going for a bag with a -50 rating, just thinking a combination of goose down and mylar would be more efficient and mean you use less goose down and have a lighter sleeping bag which is cheaper and even preform better.

Instead of a bag of a 0 degree rating at 550 grams, you have a bag that is 300 grams that has a rating of -2

I guess the only way is to make one and see, though if it was possible I guess it would already have been done.


Cheers.

Unless the mylar is going to trap air or replace something normally used in the bag and save weight, then I can't see it helping. Down is very light for its volume already, way, way less than mylar.

Mylar is the base for cuben fibre. I have heard people suggesting cuben for internal baffles in down quilts to save weight over traditional materials, so your idea is not without merit, it's just that mylar has no useful insulation value of its own accord.

I am not going for Mylar as insulation, more to reflect the heat back, the goose down will do the insulation .

Probably have to placed the mylar above the goose down for it to work, though you would have to tinker with that

Oh well, just thinking out loud.

Cheers.

I get that you want to use the aluminised Mylar (space blanket principal). I believe this is already used in the Aus Army bags which are synthetic and a similar idea is used in the OP synthetic bags with silvered fibres rather than Mylar. The trick of course is to make the Mylar breathable, you certainly want to avoid making the down damp (shredding). I have used an AMC bivvy which is good for only the coldest hours. Condensation becomes uncomfortable when used all night. I think the best use for aluminised Mylar is under your sleeping matt where heat loss is almost all radiant. This allows for a far less substantial matt but the NeoAirs seem to have that well covered.

Regards,
Ken