I really like Waxed canvas, and last year I used a very similar process to treat a pair of pants and a old army field coat. It makes your clothing water resistant, and more importantly wind proof, and abrasive resistant.
Its a old old trick, from the presynthetic days, and you still see some motorcycle gear treated this way. This works best on tight weave fabrics like denim, and canvas.
Step 1: A Simple Recipe
Equal parts: 1 part beeswax 1 part caning wax 1 part boiled linseed oil 1 part turpentine
Melt and mix together the waxes, then mix in the turpentine and linseed oil. The tin cloth mixture doesn’t have to reach a certain temperature; it just needs to get hot enough to ensure complete combination of the ingredients.
Step 2: Application Applying-Tin-Cloth Paint the liquified mixture on your canvas apron, tent, or whatever you want to waterproof. You’ll know when you’ve applied enought because it will be really easy to see when the canvas is properly saturated.
Make sure the solution is brushed on evenly, give it a quick inspection, and run a heat gun over any dope that hasn’t wicked in to the fabric. Then hang up the canvas to dry. The drying should take two weeks depending on conditions, and will feel very much like leather.