If you’ve embraced zero-waste living choices, then you already know that reusing jars and bottles is a great way to reduce, reuse, and recycle. However, some containers prove much more difficult to clean out, even if you do want to repurpose them. An example of this is candle jars—many of them come in decorative jars that would be perfect to use for a variety of things… if only you could get rid of the teensy bit of stubborn wax off the bottoms.

Simply tossing them in the glass recycling isn’t a sustainable option either, because if a glass jar still has product in it, then it will most likely end up in the garbage, so your best bet is to clean and reuse them. Here’s how.

Use your stovetop

If you’ve ever melted chocolate over the stove, then you’ll probably feel pretty comfortable with this method. All you need to do is put the candle jar in a bowl set over a pot of barely simmering water. This will ensure that the wax melts without getting the jar to a dangerously hot temperature.

You can also place the candle in a separate pot and slowly pour boiling water around the candle. Just make sure that the water doesn’t get into the candle jar itself. Once the candle melts, pour the old hot wax into something that you’re already going to throw out. Never pour melted wax down the drain as it will dry quickly and clog your pipes. The last step is to clean out the jar before reusing or recycling it.

Use your freezer

If you have extra freezer space and a bunch of old candles to get rid of, this method will be easier and more efficient than using the stovetop. First, put the candles in the freezer for a couple of hours, or until the wax is frozen. Then, use a butter knife to pop the frozen wax out of the container. You can also try to break up the wax a bit before freezing so that it’ll pop out easier once it’s frozen.

Use your kettle

Make sure your candle is on a heat-safe surface, then pour boiling water straight into the jar, leaving some room at the top. Hopefully, the melted wax ends up floating to the top. Once the water cools and the wax hardens a bit, then you can simply pick it out. Scrap any residual wax and wash the jar out with soap and water.

Use a candle warmer (if you have one)

Generally, candle warmers come with a warming base and a dish to place on top for max melts. Instead of the wax melts, place your candle jar on top of the warmer so that it melts down. Pour the melted wax into something that you have plans to toss out, or if you don’t like the idea of wasting wax, pour the left-over wax into a new candle with the same or similar scent.

Lastly, if you’re candle shopping, then you should be mindful of the packaging. Even though a candle with a pretty glass jar may be more expensive, it offers a lot more possibilities for reuse as well.