This hairspray works surprisingly well. You can use leftover lemons that have already been squeezed. The alcohol extends the shelf life of the product.
2 to 4 lemons, sliced
1 tablespoon rum or vodka
Cover sliced lemons with water in a saucepan. Simmer for 30 minutes, then cool. Strain the liquid and pour into a spray bottle. Add rum or vodka.
(Courtesy of Béa Johnson, founder of the blog ZeroWasteHome.com.)