Taken from Nessmuk’s Woodcraft
I’m pretty sure that this is cancerous, so don’t try this at home.
Three ounces pine tar, two ounces castor oil, one ounce pennyroyal oil.
Simmer all together over a slow fire, and bottle for use. You will hardly need more than a two-ounce vial full in a season. One ounce has lasted me six weeks in the woods. Rub it in throughly and liberally at first, and after you have established a good glaze, a little replenishing from day to day will be sufficient.
Waterproofing of tent material - he was not a fan of oil cloth.
To 10 quarts of water add 10 ounces of lime, and 4 ounces of alum; let it stand until clear; fold the cloth snugly and put it in another vessel, pour the solution on it, let it soak for 12 hours; then rinse in luke-warm rain water, stretch and dry in the sun, and the shanty-tent is ready for use.