Do not microwave a finished candle. The wick tab is metal. The glass is not rated for microwave hotspots. Fragrance oil does not enjoy being blasted. You can melt leftover soy in a microwave in a proper microwave-safe jug, in short bursts, if you are recycling wax — not if the wick tab is still in there.
If you are trying to rescue a tunnel
Use foil and a long burn, not the microwave. Tunnelling.
If you are emptying a jar
Freezer or hot water. Not the ping of the microwave with the tab still in. Three ways to empty a jar.
We melt wax here on a controlled heater. Microwaves are uneven. Uneven soy goes grainy. Grainy soy looks like a fault even when it is only a bad melt. If you want the wax to look like it did when we poured it, do not improvise with kitchen electronics.
