Incandescent light bulb granted a Hungarian patent (No. 34541) for a tungsten filament lamp that lasted longer and gave brighter light than the carbon filament. Tungsten filament lamps were first marketed by the Hungarian company Tungsram in 1904. This type is often called Tungsram-bulbs in many European countries. Filling a bulb with an inert gas such as argon or nitrogen slows down the evaporation of the tungsten filament compared to operating it in a vacuum. This allows for greater temperatures and therefore greater efficacy with less reduction in filament life. In 1906, William D. Coolidge developed a method of making "ductile tungsten" from
Phase-out of incandescent light bulbs has an exchange program to replace incandescent bulbs. Tunisia is reported to have a partial ban on incandescent light bulbs. Since January 2016 the importation of incandescent light bulbs has been banned in Zambia. Zimbabwe has banned incandescent light bulbs. Bahrain has banned incandescent light bulbs. Bangladesh has an exchange program. China will ban imports and sales of certain incandescent light bulbs starting October 2012 to encourage the use of alternative lighting sources such as light-emitting diodes (LEDs), with a 5-year plan of phasing-out incandescent light bulbs over 100 watts starting 1 October 2012, and gradually extend the ban to