Calcium Blinding and Laser Usage

[Prepper]

Two questions, first one on calcium blinding, on same press, same paper, same inks, we were using a double-grain analog plate no problems, switched to CTP with a triple-grained plate and immediate problems with blinding, we've been told it could simply be that the more grained plate will be more likely to blind than one that isn't so heavily grained or micro-grained whatever the terminology is. Do you all see this as probably true or no?

Second question, positive vs. negative plate. Positive plate, if I have this right, laser images\exposes all non-image areas while the image area doesn't get exposed, with most plates the non-image area is greater, percentage-wise than image, correct? If so, does that mean that the laser is used more, on for more time, imaging a positive plate vs. a negative one?

Thanks

 

[SteveAgfa]

Prepper:

WRT laser life, I wouldn't make a make a best-fit thermal plate choice based on this.

While not all imagers are the same, most often with thermal systems, the laser is
always on, and the beam is modulated/diverted/defracted away to a beam dump
if the energy for that pixel is not intended to reach the plate. Often, if the engine
is left idle, then there is an idle power state to ramp down the enegry to a stand-by
state, allowing for fast recovery to again image.

Regards,

 

[marktonk]

Hi prepper,

Not sure on the calcium, maybe the plate is just more sensitive?

With a positive plate, you are imaging the background and what is not imaged is ink receptive therefore you have to expose the plate out to the edge to burn away the background even if the image area is a small part in the center. With a negative plate, you are imaging the dots so you do not have to image to the edge.

There are allot of variables as to how much will this effect laser life, it depends on the image area, number of plates, etc.

Warning, Steve's comments lead me into a commercial "While not all imagers are the same":

With a Suprasetter, the laser is only on when imaging the plate and there is no ramp down/ramp up time, imaging is instantaneous, no waiting before imaging. Also no degradation of the laser from the machine just being turned on even though you are not imaging. As an example, last year in our demo room, I took a screen shot of the Suprasetter 105 GUI. At that time, the Suprasetter was powered on for 9,152.19 hours but the laser was only on 733.11 hours when imaging the 24,351 plates.

Regards,

Mark

Prepper:

WRT laser life, I wouldn't make a make a best-fit thermal plate choice based on this.

While not all imagers are the same, most often with thermal systems, the laser is
always on, and the beam is modulated/diverted/defracted away to a beam dump
if the energy for that pixel is not intended to reach the plate. Often, if the engine
is left idle, then there is an idle power state to ramp down the enegry to a stand-by
state, allowing for fast recovery to again image.

Regards,