Waterproofing protects material and increases its longevity. In some instances, such as when waterproofing a tent, it also helps to keep you dry. Any number of materials can be safely waterproofed for any number of purposes. With homemade waterproofing, the material you wish to waterproof determines which method to use. In some cases, the waterproofing darkens or otherwise slightly alters the colour of the material. You may wish to test a small area of the material prior to embarking on the entire project if this might be an issue for you.
Waterproof leather with lanolin or petroleum jelly. Use a soft cloth to rub it into the leather until the leather feels "dry" to the touch and the waterproofing doesn't come off on your fingers. The leather essentially absorbs this kind of weatherproofing, making it soft and supple while still causing water to bead up and run off.
Waterproof wood with a combination of one part waxed/finishing resin (as opposed to laminating resin) to four to six parts acetone. Mix resin catalyst liberally according to its directions, treating the entire mixture as if it were pure resin. Paint a thin coating on the wood, allow it to dry and repeat the process using less acetone and less catalyst each time. Wood is waterproofed when it stops changing colour with a coating, indicating that it is no longer absorbing the mixture.
Waterproof linen, light cotton canvas or hemp material with beeswax. Melt the beeswax in the microwave, place the item you wish to waterproof on newspaper, then use a paintbrush to cover the material with it. Use an old iron (one you won't be using on clothing) or a hairdryer to heat the item until the beeswax is absorbed into the fabric.
Although petroleum jelly has been used for many years by Western riders on saddles and other tack, lanolin is a more eco-friendly choice and is becoming a preference. Use disposable paintbrushes when waterproofing for ease of clean-up. Wood must be sanded after waterproofing if you intend to paint it, in order to remove the waxy surface of the resin. When properly waterproofed, the wood still feels like wood, even before sanding it.
Beeswax may be quite difficult to clean from an iron or to remove from other items. It also sticks to skin in a similar fashion to candle wax when melted, so handle it with caution. Do not use lanolin or petroleum jelly on suede leather, as it is likely to ruin the suede look.