Technical Note on Canvas for Extreme Cold

**Bradley** · 01-31-2011, 08:10

Water
Snow and ice sublimate, although more slowly, below the melting point temperature. This allows wet cloth to be hung outdoors in freezing weather and retrieved later in a dry state. In freeze-drying the material to be dehydrated is frozen and its water is allowed to sublimate under reduced pressure or vacuum. The loss of snow from a snowfield during a cold spell is often caused by sunshine acting directly on the outer layers of the snow. Ablation is a process which includes sublimation and erosive wear of glacier ice.

.................................................. .................................................. ..................

**MacEntyre** · 01-31-2011, 08:15

Bradley, I want that coat to go with my straight stock Marlin 336 in 30-30!

Youngblood, good point about sublimation. That is how ice magically disappears from things such as Shug's bib, and my wild rag, and the outside of the top blanket, when they are covered with frozen breath vapor. However, it is much more difficult for sublimation to rid your down UQ of frozen moisture when it is not on the surface. Sublimation requires a bit of air flow, else the air becomes saturated. The buildup of ice inside the UQ, that won't go away, is what's bad.

**oldgringo** · 01-31-2011, 08:19

Sublimation that you see every day: shrinking ice cubes in your freezer.

**Youngblood** · 01-31-2011, 08:48

Originally Posted by MacEntyre

Bradley, I want that coat to go with my straight stock Marlin 336 in 30-30!

Youngblood, good point about sublimation. That is how ice magically disappears from things such as Shug's bib, and my wild rag, and the outside of the top blanket, when they are covered with frozen breath vapor. However, it is much more difficult for sublimation to rid your down UQ of frozen moisture when it is not on the surface. Sublimation requires a bit of air flow, else the air becomes saturated. The buildup of ice inside the UQ, that won't go away, is what's bad.

My point is that ice will not magically disappear from things such as Shug's bib unless the conditions for sublimation exist and they do not exist just because it is cold.

Case in point for us older folks that were around when we had to occasionally take everything out of the freezer section of refrigerators and manually de-ice them because they continually froze the moisture in the air as we opened the freezer and allowed moist air to enter which allowed that moisture to freeze and build up into ever increasing ice packs. Now days the freezer section has what is called automatic defrosting, but when that was new, that was optional and at a cost.

With automatic defrosting (which is dry air circulating through the freezer) the ice will actually disappear over time from ice trays instead of building up. The build up of ice versus the disappearance of ice occurs at the same temperatures. The difference is the circulation of dry air and not how cold the air is.

**MedicineMan** · 01-31-2011, 11:33

OK I like the jacket too EXCEPT for the open butt (nicer way to put that?).
My lever of choice-Rossi Puma in .44mag, why? All I could get in stainless.
Why stainless-because I live in a rain forest

**MacEntyre** · 01-31-2011, 11:43

Originally Posted by Youngblood

My point is ...

...well made! Thanks!

Originally Posted by oldgringo

Sublimation that you see every day: shrinking ice cubes in your freezer.

Now you know why...

Originally Posted by MedicineMan

OK I like the jacket too EXCEPT for the open butt ...

It's a Duster, for horseback.

I just saw a white cotton duster at a local Western store. Me like!

**Festus Hagen** · 01-31-2011, 12:25

Originally Posted by MacEntyre

Certainly, if you use an IX Hammock Sock in extreme cold weather, you must have another VBL, such as an IX UQ, right under the hammock.

My double layer DD hammock is advertised as "waterproof" which is supposed to be a plus in case you have to use it as a bivy tent. I wonder if this qualifies it as a VPL as well? I'm sure the layer of 3/8" CCF pad I had between layers didn't hurt matters either.

**MacEntyre** · 01-31-2011, 14:25

Originally Posted by Festus Hagen

I wonder if this qualifies it as a VPL as well?

Yes!

I like to keep the vapor barrier layer in reserve, but if your hammock is your vapor barrier, you will always be using a vapor barrier! Just keep an eye out for condensation, and be prepared to ventilate if it becomes excessive.

On a trip into the Gorge last fall, I forgot my top blanket. Hickery loaned me his reserve space blanket. The low was about 40*F that night. The space blanket became soaked with condensation quickly, but I just turned it over. That happened several times during the night. I was fine!

**Roadrunnr72** · 01-31-2011, 17:39

So would it be wise to make a down UQ with canvas on the outside and nylon on the inner? It would be windproof and let the moisture out.

**MacEntyre** · 01-31-2011, 17:55

Originally Posted by Roadrunnr72

So would it be wise to make a down UQ with canvas on the outside and nylon on the inner? It would be windproof and let the moisture out.

I asked FourDog why I shouldn't put a thin wool liner in my anorak, and he said, "You eliminate the advantage of layering." Same thing with your UQ. You want to be able to remove the canvas layer when it's not so cold out.

Of course, you could have a dedicated winter UQ. I'd rather have a canvas sock, which I could use with any UQ.