Keeping Warm

If you want to keep warm in your deer stand, check out the chart below. Thermal Conductivity is how fast a material will allow body heat to conduct away from your body. So the lower the number, the warmer you will be.

FiberConductivity Notes
Polypropylene6Warmest material
PVC6.4Not the plumbing pipe.
Silk7Yea, it sounds sissy, but the stuff is pretty warm.
Polyester7.3But not that leisure suit still hanging in your closet from the 70's!
Wool8Try merino wool, it is not as itchy.
Cotton17.5Your last choice.  In fact, if it's really cold you are going to wear cotton... stay home.  In Alaska, they call cotton 'the death cloth'.

Polypropylene is at the top of the chart. Other benefits are that it does not absorb moisture and has a unique vapor transfer ability that moves moisture away from you skin and helps keep you dry.  You should also note that the polypropylene’s thermal qualities are only of value when there is trapped air space, such as when it is worn beneath regular clothing.  So if you are sleeping in your polypropylene long johns and have to crawl out of your sleeping bag when nature calls…. you are gonna get cold, so you better make if fast.  Polypropylene has a much lower melting point than polyester so you will want to avoid washing polypropylene in hot water or using the hot setting in the dryer.  For this reason, polyester materials are much easier to care for than polypropylene.

Some of the new blends combining polyester, spandex, fleece, etc. may be warmer than straight polypropylene such as Polartec, Under Armor, etc.  But I did email Under Armor to see where they fall on the chart and they kinda dodged the question so I’m not sure.

I was wondering how Neoprene compares to Thinsulate.  So I emailed LaCrosse Footwear/Danner Boots & Muck Boots.
Per LaCrosse Footwear/Danner Boots: 3.5mm of Neoprene = 300-400g Thinsulate; 7.0mm of Neoprene = 700-800g Thinsulate.
According to Muck Boots Artic Pro boot is comparable to 1,000 grams of Thinsulate. The Artic Pro has a fleece lining, 8mm CR flex-foam bootie with a 2mm thermal foam underlay add to the instep. So I’m guessing that according to them 10mm Neoprene is equivalent to 1,000 grams Thinsulate.
The above info would translate to approximately 1mm of Neoprene equaling 100g Thinsulate.