tarps

anyone make waterproof tarps with fabric and wax?

I haven't done anything like this, but I'm interested in learning.

Historical reenactors use canvas "oil cloth" to keep things dry. Basically it's a cotton canvas that's painted with boiled linseed oil, lamp black, and Japan dryer.
The ones I've used are as good or better than vinyl tarps in most every way, the possible exception being weight.
Here's a link to recipes both historical and more modern. Hope it's of some use......

http://44tennessee.tripod.com/articles//oilcloth.pdf

My brother once made some wax signs for his store they were cheaper than laminated paper and lasted for months in the snow and rain. For a tarp I think you would need a very oily wax (more malleable and less prone to cracking and crumbling off). Something like toilet seal wax I think would be best. I once made a lip balm out of pig lard and wax thatès what you need fat and wax mixed. I doubt you can make it for less than the plastic stuff though.