Plate Densitometer

[sayers]

I am interested to find out how many people check CTP plates. especially thermal plates to see if the screens values are correct.
I used to check film once a week due to focus of the laser and chemistry but have not been checking plates.

How often do you check and how often does the laser need to be corrected to adjust for correct reproduction on plate.

 

[Cory Smith]

Re: Plate Densitometer

I try to check a plate once a week, doesn't always happen... a few times a year a tweak might be needed, but most the time we are within +-1-2% which is fine for me.

we never tweak the output device, just the curves on the front end.

 

[disbellj]

Re: Plate Densitometer

We change chemistry on our Screen every 600 plates, and for a little while I ran a test plate every 150 plates. But because they don't change much at all (like has been said, within 1-2% and 2% is in tolerance while 3% is out-of-tolerance), I only check the first plate after changing chemistry and may have to put a plate curve for calibration (to make a 50 be a 50) in addition to the bump curve we put to match our old film output or GRACoL2006_Coated1. Our platesetter automatically adjusts the laser to keep in focus mainly. We've had someone come out a few times in the last four years, and each time I get them to check focus while they're here for maintenance, etc.

Don

 

[GinSu]

Re: Plate Densitometer

Our operator who runs our Javelin platesetter is anal about the calibration and checks every single plate. That being said, we haven't had to recalibrate once since its initial install three years ago.

 

[DavidMa]

Re: Plate Densitometer

We check every plate.
Only re-cal the lasers when something breaks.

We also (like Cory) will make minor adjustments to the output curve before doing something to the lasers.

 

[G_Town]

Re: Plate Densitometer

We check the Black plate on every job and log it in a book to track %'s

In the past I used to go for a week without checking then I got a batch of bad plates/chemistry and had a whole slew of color issues on press.