Specks can occur when the candle dye hasn't completely dissolved in the hot wax. Unlike fragrance oil, you can add dye blocks or liquid dye right to the pot while the wax is heating. Gently and thoroughly stir until the dye has completely dissolved. Since most of the specks remain at the bottom of the pot, when you are finished pouring your candles, discard any last bit of remaining wax if you notice any specks of unmelted dye.