Unforeseen rainfall can, at the least, drench your coat and other garments and, at the worst, ruin your coat if the fabric is not made with colour-fast textiles or if the water creates calcium stains. Luckily, you can shield yourself and your coat from water damage by adding waterproof protection to your favourite jacket. By following just a few basic steps, even somebody without prior fabric treatment knowledge can protect a coat for extended outdoor usage.
Clean the coat following the preferred cleaning method indicated on your coat's "care tag." Treating a dirty coat leads to less effective water resistance.
Hang your coat in a dry area with good ventilation. According to Fabric UK, a distributor of Scotch Guard water repellent products, Scotch Guard is "odourless when dry," but a "slight odour is noticeable until dry." The fumes are not very harmful, but keeping a window cracked will help the smell dissipate more quickly.
Lay newspaper or a drop cloth beneath the coat to prevent waterproofing spray from getting on your carpet.
Spray the entire coat with 3M Scotch Guard Heavy Duty Water Repellent for Outdoor Fabrics (see resources). The outdoor fabric spray is more protective against rainwater than the indoor variety, so make sure you get the right type of spray.
Wait for the coat to dry before handling it. According to 3M, the maker of Scotch Guard, Scotch Guard spray products typically take 24 hours to dry. Your dry coat now features a "durable water barrier" to keep the coat "drier, cleaner, and newer looking longer," according to Fabric UK.
Do not use Scotch Guard spray on suede; ask a dry cleaner or tailor for advice on professionally waterproofing suede fabrics.