The lifelong collaboration between Louis Poulsen and Poul Henningsen (1894-1967) began as early as 1924. As an architect, writer and cultural critic, Poul Henningsen was one of the first to recognise the importance of shaping electric light. After his revolutionary development of the three-shade system in 1926, he further developed the system in 1958 and designed the PH 5 pendant lamp. After analysing the reflective qualities of light, the important Danish designer designed an innovative lamp characterised by its totally glare-free and symmetrical lighting properties. His constant work in lighting theory with structures, shadows, glare and colour indication, and with the human experience of light as the centre of it all, is still practiced today at Louis Poulsen.

Poul Henningsen was and remains the most significant designer for Louis Poulsen. The ideas behind his iconic designs form the basis of the company's lighting profile to a large extent. He was also a strong cultural personality of his time who, in addition to his passion for "the good light", extended to revue, social criticism and satire. The collaboration between Louis Poulsen as a manufacturer and Poul Henningsen as a designer lasted throughout his life.
In 1926, the three-shade system saw the light of day for the first time at an exhibition in Paris. The lamps were created as a collaboration between Louis Poulsen and Poul Henningsen. Throughout his life, PH sought to promote glare-free light and direct it where it was needed. He created not just a lamp, but a complete system, and over the years around a thousand different lamp models were produced with this shade system. The three lampshades are all made of mouth-blown opal glass in three layers. The inside is clear sandblasted while the glass is white in the centre and clear glossy on the outside. Together, the three layers create a beautiful diffused light both upwards and downwards. The numbers in the lamp names refer to their shade sizes. The PH 3½-2½ has an upper shade of approximately 35 cm and Louis Poulsen first introduced it in its current form in 2002 in high-gloss chrome-plated and in black metallised in 2017 and most recently in metallised brass in 2019.
Please note! Brass is a natural material and as such it changes in response to its surroundings, which is why the brass surface will darken and become less shiny over time. This is a natural process where each lamp will acquire its own individual patina. However, if you want the surface to be shiny and bright, you can do this with a brass polish, but be sure to: use a special polish suitable for brass or copper; use a polish with as little abrasive as possible; use a soft cloth for both rubbing in and polishing; use the gloves provided to keep the lamp free of fingerprints.
OBS! As the glass is mouth-blown, air bubbles are allowed in the glass up to 3mm.