2017-08-17

howto: Waxing cotton 2


A while back I wrote this article on waxing cotton:
http://www.blog.smalladventures.net/2017/02/waterproofing-cotton-poncho-experiment-2.html

I'm not actually using that poncho, I decided it was okay, but a little bit heavy. After doing extensive calculations and agonizing about it I've decided on what I think will be the lightest solution.

Instead I'm using:
  1. A cotton canvas overshirt, which I treated with wax as a raincoat
  2. 3x5 800 threadcount sheet, which I've treated with wax as a groundcloth, and to surround my gear when it's tied to my pack, to keep it dry
  3. 5x8 800 threadcount sheet, untreated, as a shelter while sleeping



The reason this works out well is a little complicated. A poncho needs to be worn while hiking, so it cannot double as the waterproof layer for gear while hiking, as a result I would *also* need fabric for that. Additionally it's so large that it's a waste to use it for a groundcloth, so I'd need to have a treated ground-cloth that I also use to keep my pack dry *anyway*. The poncho is so heavy that compared to an untreated tarp of the same size + a treated canvas raincoat is only a bit heavier. But, the treated canvas raincoat is useful as a windbreaker too, where the poncho is not.

Yeah... this is why it took me a long time to figure it out. I had to actually calculate theoretical weights for a number of different gear combinations to decide in the end.

Anyway, end result is that I've treated yet more fabric, and in the process I've figured out a few more things with respect to treating cotton, including a somewhat simpler/faster process.

In making the new tarps I wanted to try turpentine, as mineral spirits is made from petroleum, while turpentine is made from tree sap. This treatment worked extremely well, penetrating the fabric with wax in just one coat, I applied a second coat for good measure. This is a far cry from the last treatment I used that seemed to work well, and I believe the reason is that terpentine seems to dissolve beeswax better than mineral spirits does. Here's the recipe:
  • 1 quart of terpentine
  • 1/2 pound beeswax
  • 1 tablespoon or so pure (dietary suppliment type) linseed oil

Note that I'm using the linseed oil just to help fight mildew, rather than as a major component to help with flexibility as most recipe's do. So far flexibility hasn't proven to be a major issue though, and the smell takes months to fade, so I keep using less each time I treat something.

This worked so well that I re-coated my jacket as well, hoping to get more waterproofness out of it. I'll report back on how well it actually works in the rain, but initial results are that the wax filled the gaps in the fabric well, and don't appear to be sitting on the surface such as to flake off.



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