Ah, you want to bestow upon your chair the magical, liquid-repelling force field known as Scotchgard? A wise move for anyone who enjoys beverages, food, or has pets, children, or clumsy friends. While one of your provided sources was a wonderfully unhelpful YouTube page, the official Scotchgard site gives us the real game plan for victory over stains.
First things first, you can't just spray and pray. Your chair must be clean and completely dry before you begin. Applying protector to a dirty chair is like putting a raincoat on over muddy clothes; you're just sealing in the grime. Once it's clean, find an inconspicuous area to perform a spot test, like the fabric underneath a cushion. Spray a small patch and let it dry to ensure it doesn't decide to redecorate your chair in an unfortunate new color.
With a successful test in the books, it's time for the main event. Make sure you have plenty of ventilation, as the fumes are no joke. Open windows, turn on a fan, or drag that chair out to the patio. Shake the can vigorously, then hold it upright about six inches away from the fabric. Spray in a slow, sweeping motion, overlapping your passes to get an even, but not soaking, coat. Think of yourself as a methodical artist, not someone trying to put out a fire.
After applying the first layer, let it dry completely according to the can's instructions. Patience is key here. Once it's fully dry, a second light coat is highly recommended for an extra layer of "oops-proof" protection. Let that dry, and your chair will be ready to face the world, valiantly repelling spills and making you look like a domestic genius.
