Okay, one point I learned about heat sources. Candles heat even and slow, stove burners fast and uneven, butane lighters slow and had a lot of problems if I was using it too long. Torch lighters would melt an eye hole before the jig head would heat up evenly. Large wick candles would leave too much soot and ruin any paint job I tried. Too much humidity in the house on a day after I made dinner and boiled something ruined everything I powder painted.
Painting after I had eaten anything greasy and not washing my hands would leave bald spots and pot marks. Peeling citrus fruit or a banana between paint jobs, better off painting the fruit peels.
I plan on getting an alcohol burner and hopefully it will be my last purchase for powder painting everything. I love candles but trying to keep an even flame for a long period is a pain. It is slower no doubt but for me it will be the best way and safest. For you, a heat gun might be best.
You really have to experiment and find what works for you the best and that way you have a second best way to fall back on. I tried a heat gun, melted 4 consecutive heads in less than a second at 1/8 ounce and will not use one again. I shake too much to be using one anyway and with little ones around the alcohol burner is so much safer and they can even help when I use it.
There are a hundred different things that can affect your painting, 75 of them won't tell you what you did wrong and you may never know what causes it.
I had a batch of spinner blades that I did and about an hour later I did another batch. The first 25 had streaks, holes, pot marks and everything else when cured. The other 25 did not and came out perfect. I was lucky to figure out what caused it. The first 25 I had pet my dog right before starting and touched the blades all over the place. In the hour between I had lunch and washed my hands. I touched my dog the next day and touched a spinner blade and it left oil marks all over them. Dumb luck I figured it out, most of the time I chalk it to Murphy's law and don't even look for an explanation unless one seems completely obvious.
I love taking my kids fishing, now if I could just manage to fish at the same time.