Commercial processors filter their wax under high pressure.
They have the equipment to handle large quantities of dark wax under controlled conditions. As a hobbiest beekeeper, we have several ways to lighten the color of wax. First choice would be to place the wax in a solar wax melter and let the sun do the work for us. This process takes some time and results in a sun bleached wax of high quality. Second choice would be to heat the wax in a double boiler keeping the temperature under 160 degrees.