Does anyhave more info regarding Philips color 38 Kolorite (color temperaure, CRI)? I found a Philips 40W T12 tube (Hamilton, UK made) from the 1960s. Never heard of color 38. Would this be a De Luxe color with CRI > 90?

Hi Lampwiz: here you'll find this colour listed here:
http://lamptech.co.uk/Documents/FL%20Colours.htm

As far as I know, Philips tubes marked Colour 38 are actually made by Thorn. 

Originally, AEI Mazda developed the Kolor-Rite 38 design in the 1960s and Philips quickly followed with a very near equivalent, Trucolor 37, whose colour rendering and efficacy were both better but the colour point was slightly off-white.  There was a battle between the two manufacturers for many years, and in the early 1980s UK Govt specified that the KolorRite tubes should become the standard lamp for lighting all hospitals and other large public buildings where good quality neutral white light was required - presumably because their colour point was more neutral.  From that moment the sales of Philips' Trucolor 37 declined and Thorn's Kolor-Rite 38 took off.  To avoid the loss of business, Philips thereafter replaced its Trucolor 37 with Trucolor 38 whose colour was exactly the same as Thorn's Kolor-Rite 38.

Certainly in the late 1980s the Philips Trucolour 38 tubes were being made for them by Thorn, so are you sure that yours is really from Hamilton?  Does it have the factory ID symbol of that site?  Since Thorn also sold the phosphors made at its Elgar Lamp-Chemicals division in Enfield to other lampmakers it is quite possible that they may have sold their Kolor-Rite phosphor blend to Philips, but as far as I know, they actually made the whole tube for Philips.

Hi James,

sorry for my late reply.

The tube is a Philips Trucolor, not a Kolorite. I somehow mixed up these two commercial names.

The tube does have the Philips Hamilton factory ID (circle with a dot inside) en date code K7 which corresponds with October 1987 for this tube. The full etch reads: Philips 4FT 40W/38, Philips logo, TRUCOLOR Made in GT Britain.

The phosphor has a kind of granular look, it has a coarser look than the usual Philips tubes I have seen so far. But I don't think Thorn would copy the Hamilton factory ID if they indeed made this tube...