If the depth of your melt pool at 4 hours was over an inch, the wick is too big. It is advisable to strive for a melt pool 1/4 to 1/2" deep. I try to keep my mp's around 1/4 to 3/8" so that it doesn't get significantly deeper even with power burns. Like Brenda said, the wax will tend to catch up with subsequent burns, as you get to the narrower part of your jar. I'm not sure how much you've explored this message board, so I'm throwing in another tip. It'd be easier if you don't wick your jars when you pour them. Once they've set up, you can poke a hole in the center using a skewer, stick a wick in, then use the heat gun to hold it in place. That way, if it doesn't look like the right wick, you can easily yank it out and replace it. Don't be too quick to pull out a wick though. I like doing multiple burns before I make a decision on a certain wick.