Ever wonder why some canvas, like the stuff that a Carhart jacket is made of, is so much tougher than, say, a drop cloth? The secret is 'tincloth,' invented in some year by some guy --probably an American-- who needed something tougher than canvas or denim-- tough enough for fighting dragosaurs with a claw hammer on horseback across the Great Plains. Tincloth is that kind of tough stuff.
To demonstrate the wonder of tincloth I took a shower in my clothes and tried to set myself on fire. Allow me to explain...
Step 1: A simple recipe
beeswax (I used toilet gasket rings for this. Done dirt cheap.)
boiled linseed oil
(Optionally you can add turpentine. I saw it referenced in a few places while I was doing my research. I opted against using it since it seemed to increase drying time.)
Melt and mix the beeswax and the linseed oil. It doesn't have to reach a certain temp, just hot enough to ensure complete combination.