Each waterproofing product is a little different—some are applied to wet products and some to dry, for example, and they each require a slightly different optimal spraying distance from the item—so it’s important to read the bottle instructions before you begin. In most instances, you’ll need a well-ventilated outdoor workspace for application, and you should cover that workspace with something like a tarp to keep the product excess contained. Many items require at least 24 to 48 hours of time to dry before you can use them again, so planning ahead before a big trip is crucial.  If you’re concerned about changes to an item’s color or texture, spot-testing on a small area is always a good idea.  Before you waterproof an item, any item, an important note is this: Make sure it’s clean first. Dirt and oils leave residue on the surface of your gear, even if you can’t always see it. And use a detergent that won’t leave a residue since that can impede the waterproofing product from working. Most brands sell their own washes in addition to the sprays. “A great analogy we like to use is you wouldn’t wax a dirty car so you wouldn’t waterproof a dirty item,” Allen explains. “While the waterproofing is the cool part of it all because you can see the beading, people forget that cleaning is the first, most important step in the waterproofing process.”  And in some instances, you might find washing is all that’s necessary. Putting your waterproof clothing in the dryer can also help reactivate the DWR coating.  “A lot of people spend money on outerwear, and then they’re afraid if they wash it too much it’ll damage it,” says Steve Nagode, an innovation engineer, and former REI test engineer. “That’s a really common concern. But the key is keeping it clean because dirt and smoke and particles break down DWR. If you stand in front of a campfire, all of a sudden your jacket might not work.”