1968 Philips 200PS/DB (200 W / 220 V)

Incandescent lamps with naturally colored glass bulbs were made as far back as the 1890s for decorative lighting purposes. It's only in the mid-1910s that blue glass with cobalt additive was used to filter the warm-white light of incandescent lamps to produce light with a high color temperature specifically for color critical lighting applications, such as in the textile industry. Those so called daylight blue lamps were first introduced by GE of America and by the 1920s many other lighting manufacturers offered similar variants while the lamp became commonly used in general lighting applications as well.

During that decade Philips (the Netherlands) offered no less that ten different models of their "Zonlichtlampen" (sunlight lamps in Dutch) ranging from 60 to 1500 W. That extensive range was eventually reduced during the 1940s and 50s as daylight fluorescent tubes became more suitable for color critical lighting applications. Not only were the new discharge lamps far more efficient than their incandescent counterparts, thus reducing power usage and infrared emission considerably, light of actual daylight color could be produced whereas that obtained from cobalt blue GLS lamps was only a gross approximation of daylight, better classified as neutral white (i.e., CCT around 4000 K).

By 1955, Philips's range of daylight blue lamps comprised three main models only, rated at 60, 100 and 200 W, and aimed at the less demanding domestic and commercial applications. The largest model, shown here, was eventually phased out in the late 1960s as demand for large daylight GLS lamps dwindled in the general lighting market. The range was eventually extended towards lower wattages down to 15 W around the mid-1980s so as to better cater for all sorts of domestic lighting usages, including ambiant TV illumination. Those lamps eventually became niche products towards the late 1990s and by the early 2000s Philips reverted back to its 1970s lineup by keeping only the 60 and 100 W models in their commercial listing.