a 68w H&H 16000 hour traffic signal bulb was burned base down 24/7 for about 4 years. Was used in a storm water pump station indicator with a green glass globe.
Wow it did pretty well! My great-aunt's kitchen has a two-lamp drum light with two incandescent lamps and the lamps were dimmer than 40W incandescents because the inside of the glass was "smoked" like this from filament evaporation(?). A pair of new 75W lamps and her kitchen was MUCH brighter!