How to Reproof an Outdoor Jacket with Nikwax Waterproofing. It is time to test out some Nikwax waterproofing products, which were kindly given to me by Nikwax. Nikwax is the world Leaders in waterproofing. You can read all about my detailed product review and how I reproofed an old outdoor jacket. Breathing new life into it and saving money on buying a new one.