You may recall I made a rainshirt a while back: http://www.blog.smalladventures.net/2015/12/diy-raincoat.html
Well, now it's been pretty well tested. I've used it in rainstorms while hiking or hanging around in camp, I used it winter backpacking, skiing, and dogsledding e.g.:
With a layer of wool under it, I found the shirt works in light to moderate rain. In a really heavy downpour I still get wet, but it's still VERY useful, so useful that with this and a poncho I'm completely satisfied with my rain-gear.
It does have one issue though. Because I didn't trust that I would like the result, I used a very old worn out shirt to do it (bought used ~2009 or so by the person I got it from about 3'ish years ago), which is now torn on very nearly every seem. I also really didn't like the method I used, so more experimentation was needed.
If you've seen my experiments with linseed oil http://www.blog.smalladventures.net/2015/11/linseed-oil-for-homemade-oil-cloth.html, I was pretty nervous to try that again, and that's what most of the directions I could find online said... But after some digging I found some other recipes, and some more detail. Bees-wax is more waterproof, but very stiff, linseed is more flexible, but not as waterproof, thus people mix the two to get the ideal balance they want. That sounded a lot better to me. I also learned that some folks mix it with mineral spirits to get it in to the fabric, simplifying that whole process. So I decided to give it a shot. This recipe also uses pure linseed oil, not boiled, so I could be assured it was the pure stuff. It's maybe 50% mineral spirits 50% wax, using about half a pound of wax, and then a couple tablespoons of linseed oil (flax and linseed are the same thing).
All 3 ingredients are pretty flamable, so I wanted to be careful. After considering a lot of options my mom happened to have an old crock-pot she was going to get rid of anyway, so I went with that... allowing me to do it outside and keep all the fumes outside. Note that this probably *could* be done over a fire, just be very careful (easy to do, since you know... it's a fire... outdoors).
The mineral spirits make it more of a soft paste, and while hot it's quite liquid, this way I was able to simply paint the stuff on, and it soaked in to the fabric a bit instead of becoming clumpy on the outside like the otter wax did.
The picture above is just after waxing. I then let it cure in the sun for a couple of days... interestingly with the mixture I used the wax flowed a bit and soaked in a lot more, darkenning as well probably as the linseed oxidized. Now there's almost no clumpyness at all and the wax is well embedded. After ~4 days the linseed smell is greatly reduced, but still a little more than I like. I'm hoping that after more cure time (maybe a couple of weeks) it'll fully resolve. It is yet to be seen if this mixture works as well or better than the otter-wax, but I have high hopes!