Zalin - Sounds like it could be oilcloth, or waxed cotton. I think the names are sometimes interchanged. Oiling was the original process. After wax, other than beeswax, became available that was either added to the mix or used as a replacement process. And most of this stuff was either folk methods or trade secrets, neither of which are commonly documented.
Bunny - Yes, I think the drover's coats and chaps in waxed cotton are fairly popular in Australia. If they use the cupro-ammonia process it is my understanding that a dark cloth is the result. The waxing process does result in some darkening as well.
If you woods walk you are probably familiar with getting into a bramble of blackberry and how the thorns catch on your pants and then when you move forward the interlocking canes are pulled along and attack your upper body from the backside? The waxed duck greatly lessens that problem because the thorns just slide by your legs and so you aren't subsequently attacked from behind (or the side). I went from avoiding whole woodlands that were infested with multiflora rose or thick with blackberry to not even paying attention to where I'm walking. And even at that I usually return home unbloodied.
I usually carry either my waxed messenger bag or a cordura day pack for tools and collections and I use that as a shield to fend off the errant cane or vine and together they have just made it so much more enjoyable.
bessiecrocker - the well known downside of trusting my memory. You are absolutely right, I meant Barbour not Burberry. I didn't know they called rayon Cupro in Europe. That is an older process, perhaps more favored in Europe than in the USA. I think there may be only one or two plants that still use that process due to pollution issues.
Here is a link
to one dressing compound. If you look at websites that sell waxed cotton they usually have the dressing for sale somewhere on the site. I don't know much about it. Some sites may supply a bit in the way of application details. I think some clothing that is sold now as waxed is described as dry waxed. I think that is more related to "Scotchgard" than to wet waxed cotton.
The waxed cotton I made does feel waxy when it is fresh. That faded fairly quickly with use. It could be that mine isn't waxed heavily enough to be as waterproof as some, but I was mainly interested in the thornproofing and it has worked admirably for that. I will say it is heavy, but it is made out of heavy cloth to start with so I guess that is to be expected.
I don't think the names oilskin or waxed cotton or oil cloth are regulated. So I think there is a local variability in what they mean and also a variability in the production materials and methods. When I was searching for the methods to make this I did run across a lot of listing for Australian drivers coats or dusters.