Monitor warmup

I’ve heard it’s necessary to allow a CRT to warm up for 30 minutes before you can trust the colors and brightness. How about an LCD?

There are so many unanswered questions about LCDs. How long to they last? How often do they require recalibration, etc, etc.

I have heard some manufacturers recommend 30 minutes for LCDs but I’m not sure if they are echoing CRT recommendations or there are real reasons behind it.

I think it couldn’t hurt to leave it for a while prior to calibration. You could also take measurements of a white patch over 30 minutes to see if there is a measurable difference.



A CRT is a glass envelope containing a partial vacuum. The three colour guns have heated cathodes which emit the electrons that form the beams. Beam current stability and therefore image brightness and colour balance, drifts quite a bit until the temperature of the whole tube has stabilised. The tube temp changes exponentially after its turned on, so it makes it a bit difficult to say exactly when it’s stable.

LCDs have cold cathode backlights. Again these are glass tubes containing a partial vacuum. Although they have no heaters the ionised gas inside them that causes their ‘white’ phosphor coatings to glow still heats the tubes and brightness will gradually increase as they get up to a stable temperature. This is similar to the situation with CRTs although the backlight tubes and the rest of the LCD probably have less thermal capacity than a CRT so they may warm up and stabilise a little faster.

I kept my calibrator on my 3 month old Lacie 526 and it didn’t stabilize to match the calibrated profile for about 20 minutes after it was turned on for the day.