Strip paper labels and sticky residue off glass jars with a warm soak and an oil-and-baking-soda paste.
Fill a sink or basin with the hottest tap water you can stand and a squirt of dish soap. Submerge the jar fully and let it sit for 20 to 30 minutes. The heat softens the paper and loosens the adhesive underneath.
Lift a corner with your thumbnail and peel the label off in one slow pull. For stubborn paper, scrape it away with the edge of an old plastic card or a plastic scraper so you don't scratch the glass.
Mix equal parts cooking oil (or baking soda and oil into a paste) and rub it onto the leftover gummy adhesive. Let it sit 5 to 10 minutes — the oil breaks down the glue. Rubbing alcohol or a dab of nail polish remover works fast on tougher residue.
Scrub the loosened residue off with a sponge, then wash the jar in fresh hot soapy water to cut the oil. Rinse and dry completely. The glass should be clear and smooth, ready for storage or crafts.