So I have some preety white/yellow wax that im trying to melt down. I used a medium box, with a piece of glass over the box. No matter how long I leave it out in the direct sun with it being 90 plus degrees nothing will melt. I can't figure out why most people say it only takes 20-30 mins and it will melt in direct sunlight. No matter what I try I cannot get the wax to melt. Any suggestions?