It’s an additive for paraffin wax to reduce the air bubbles and make your candle turn out more clear. If you buy the blended paraffin wax they usually already add it.
You put too much gold leaves at the beginning. That’s why quite a few pieces are floating in the wax. It’s wasteful. You also must have poured at much hotter temp than 90c. If you actually poured at 90c, a lot more of the white color would remain, and you have to wait a bit more as the top part was not hardened. You can also do a second pour to fill the indentation then flatten the bottom.
