First, you're going to wait about an hour for the candle remnants to freeze. Once frozen just stab the wax inside with a butter knife and it should break into a few chunks. Just shake them out of the jar into a bowl. You can throw them away, use them in wax melt holders, or even re-use them to make fire starters.
Next, let the glass come back to room temperature and heat some water on the stove. You'll want it hot but not quite boiling. (boiling water can cause the glass to shatter) Place the jars in your sink and pour the water into the jars till full. Now you just wait for the wax to melt.
While waiting on the wax, get a bowl and dump some ice cubes in it. Once the wax is melted, slowly pour the water into the bowl. You may need to use a pot holder or oven mitt to hold the hot jar. The wax should solidify and float to the surface in little pieces. Strain it out and throw the wax away so it doesn't clog your drain.
Your jars should be mostly clean now. A squirt of dish soap on a scrubbing sponge and some warm water should remove any streaky marks or soot on the jars. If they have labels now is the time to remove them. They should peel off easily since they're wet. If there is residue left behind just apply a little bit of cooking oil, let it set a few minutes and wipe off with a paper towel. (you could use Goo Gone or WD 40, but I prefer plain 'ole cooking oil) You might have to wash again with dish soap to remove the oil. Let dry and use them for whatever you want!
That was easy, wasn't it? Now why in the world did I wait so long?
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