not a stupid question at all. no you can not, it will not take the heat and will melt or just outgass horrible, you can lay powder over JB weld if you get the right stuff but only for powders up to 375. we typically will braze the item, or use a metal fill, then primer, then powder.
finished product, exhaust end cap, swing arm, upper stay, frame support rails!
finished product, exhaust end cap, swing arm, upper stay, frame support rails!