For a stoic guard against stains and water marks, give your dining room upholstery two good coats of Thompson Fabric Seal Spray. Water, soda, and condiments will bead and slide off the surfacethough we don't recommend this procedure for suede.
Notebooks and Paper
You can preserve letters or documents by waxing them with a candle, or applying a coat of alum (find both tutorials here). If you need a weatherproof notebook, take a cue from the U.S. military: Grunts have carried Rite in the Rain Memo Books for years.
Denim or Canvas Apparel
To waterproof natural fabric like cotton, denim, or canvas, give it a thorough rubdown with a bar of Otter Wax. The wax won't leave any residue, but will stiffen and darken the fabric to give it a rugged appearance: We recommend denim shirts, work jackets, and old canvas weekenders.
While leather can never be fully weatherproof, there are several treatments that will help it survive some contact. Condition it with mink oil every month or two, and give it a coat of spray protectant if you expect inclement weather (Note: The spray should be reapplied every 8-10 uses). If you don't mind a darker finish, natural beeswax conditioner is even more effective.
Boots and Shoes
To weatherproof a pair of brogues, or a pair of wingtip dress boots, spring for a leather preservative. To weatherproof your work boots for next to nothing, apply a layer of wax from the hardware store while the leather is warm and dry.
Numerous cases claim to be waterproof, but we recommend investing in a wetness guardlike those made by Watershotespecially if you plan on any underwater photography. For something less intense (and far more subtle), Liquipel will give your phone an invisible, waterproof coating with a 1-year guarantee.
Like any other possession, raincoats are subject to wear, and your average coat will need a yearly treatment to maintain its waterproof coating. Luckily, the process is easy to learn and won't require many supplies: This article in Popular Mechanic lays it out step by step.
The internet has long been abuzz over NeverWet, a silicone nano-coating that can waterproof (really, truly waterproof) just about anything. The coating only lasts for a limited time, but its power is a wonder to behold: Syrup slides off cotton shoes like rain off a glass window. Buy it in the form of a versatile spray and see how it comes in handy.
Copywriter, cold brew advocate, purveyor of handcrafted birthday haikus since 2009.