Winter sock material?

[MacEntyre]

Some of us have had difficulty finding 4 oz canvas. Can you point us to any online sources?

I get it by the roll from Boone Fabrics, a retail fabric store in Greensboro.

2questions for you Mac.....imagine that!

First, after reading your explanation about temp and humidity differentials and the benefit of canvas to achieve equalization of the differential, do you have an opinion which of the two is more important? Is the humidity differential more of a concern than the temperature differential? If so, could I assume that anytime it would snow...versus rain I would be better off using a canvas sock than a VBL?

If there is a possibility of water in the liquid phase, do not use canvas. That's why I say it's good for conditions below 20*F.

Secondly, have you tried to dye the canvas? I bet the canvas would dye well....you know for those who prefer the stealthy appearance?

I have not!

Tim, Mac or Fourdog can speak to this better than I, but I believe the benefits of canvas start well below the temperature at which it might snow. This is real cold weather technology. For temps down to zero I'd use Pertex or Momentum 90.

I say below 20*F, whether it snows or not. FourDog says below zero. I believe his viewpoint is that weather can warm up, and then you have the wrong gear. The point is that canvas is no good when water can achieve the liquid phase.

My question about using canvas primarily for extreme cold may not apply to socks used under tarps. I may have been thinking of canvas tents or anoraks used without additional waterproof layers. That's when you really don't want to have rain or even heavy wet snow.

I don't find a tarp useful below 20*F, when I use a canvas sock... except as a wind block.

Between the discussion of hydrophilic down treatment in another thread and the technical note above I'm thinking there must be a rule of thumb about relative humidity that determines the choice of fabric type for a sock.

If you look at the psychrometric chart, you will find that the absolute humidity in extreme cold is ridiculously low, making the differential between ambient conditions and your skin huge. The over riding concern is to get rid of the water vapor in a way that prevents it from freezing in your insulation. You need high vapor permeability.

- MacEntyre