Gregg Wallace is in South Shields at a clothing factory where they produce 650 waxed jackets a day. He follows the production of water-resistant jackets from the arrival of 500-metre-long rolls of undyed cotton through to dispatch. Along the way, he sees the fabric dipped into baths of wax heated to 95 degrees Celsius and learns how a 23-piece pattern is used to create a complex 3D jacket jigsaw.Meanwhile, Cherry Healey is learning about the science of staying dry. She finds that it is easy enough to waterproof a fabric by coating it in a non-permeable coating. But while this stops water getting in, it also stops sweat getting out. The key to comfortable rain resistance is a breathable membrane which contains microscopic holes, big enough to allow steam to escape, but too small to let rain drops in. Cherry also visits an umbrella factory, where manufacturing methods have barely changed in 150 years. She helps transform a simple wooden stick into a top-notch canopy using saws, pliers and needle and thread.Historian Ruth Goodman is investigating the fishy origin of waxed jackets. She visits a remote Scottish harbour and learns how these weatherproof coats were born out of oil covered sail cloth which seamen adapted into garments to keep out the worst of the weather. She also visits Edinburgh and learns how an English King played a key role in the popularity of that favourite Scottish fabric, tartan.