Thank you, Malcom. You're right, the whole thing needs to be assessed, not just the tubes. I superimposed the spectrum image you sent with the one from my humble Excel sheet (tried to aligned them at 560nm) and it is clear that the new tubes have more energy around 360nm. https://1drv.ms/u/s!AkD78CVR1NBqkLUuwGMsH5ObGTay4A I still wonder what the visual difference is like, the same print viewed in two light booths, one with the old lamp and one with the new, E tubes? If the substrate incorporates a lot of OB, like b* = -6.00, the booth with the new lamps should make all color appear "bluer" overall, right? / Roger -----Original Message----- From: colorsync-users <colorsync-users-bounces+graxx=videotron.ca@lists.apple.com> On Behalf Of Malcolm Mackenzie via colorsync-users Sent: Monday, June 17, 2019 5:00 AM To: colorsync-users@lists.apple.com Subject: Re: colorsync-users Digest, Vol 16, Issue 35 Re; 1. ISO-3664:2009 illumination (graxx@videotron.ca) Hello Roger Just to add, if the luminaire uses a glass or plastic cover you have to check if it is effectively UV filtering. Most old and many modern ones are. Below is a GTI reading, no glass which is 3664:2009 compliant. [image: GTI.png] regards Malcolm Mackenzie Colour Engine