what spray for laser overprinting

[Paultheprinter]

hi there,

had a few issues today with a job going through a laser after 4 col printing, job was 4/4 w/turn on 250 silk only 2000 sheets, ran 2v spray on job at 3% as i wanted to keep sheets as clean as possible, does anybody know about the correct type of spray for laser overprinting? all help gratefull

Paul

 

[leetaylor]

hi there,

had a few issues today with a job going through a laser after 4 col printing, job was 4/4 w/turn on 250 silk only 2000 sheets, ran 2v spray on job at 3% as i wanted to keep sheets as clean as possible, does anybody know about the correct type of spray for laser overprinting? all help gratefull

Paul

Great question, which I hope someone can answer!

We recently had the task of overprinting LOTS (around 300,000) of pages, that had been Litho printed in four colour process, on our Xerox 4110.

At first it ran like a dream but after a while we kept getting, what appeared to be, paper jams.

In reality it was spray that was covering the machine's sensors, tricking it into saying the sheet had jammed.

The only solution was constant spraying of air into the machine to blow the spray off off the machine's sensors.

Sorry to waffle on! But would love to hear a solution to this question!!

Thanks Guys!

 

[nhprinter]

tough question

tough question

We don't run too many offset jobs through our Cannon 7000, but we haven't had any problems the few times we have.

I'm not sure what the best powder is, but if your presses are using silicone coated powder I'm sure it would be a problem. That would be the first thing to check.

We use a 25 micron spray powder from AirTech in our OxyDry systems. It's one of the best powders I've ever used for not building up on the blankets on the second pass so I would think that that's also a plus for going through the Cannon. We use to use it on our DI which was notorious for powder buildup on the blanket because of the lack of water.

They also make a sugar based spray that suppose to dissolve. I don't know anything about it, but I know it's been discussed somewhere on this forum.

Hope that helps

 

[GazKL440]

De-spray it, ie run it back thru the press on impression with rollers disengaged to take the spray back off the job... unless the run is pretty big of course but 2000 odd wouldnt take long..

 

[Paultheprinter]

hi there,

the 2v is the water soluable powder which you have heard of, the job had so little spray on that it would have set off, my thoughts would also be to avoid coated powders due to the silicon in them and to stick with regular but due to the fine tints in the grip edge i wanted to avoid spay lines building up, thanks for the input everyone but tommorow ive got the job back on for 200 a5`8 up so its a colour match (purple) for 25 sheets work and turn probably with only 125 sheets to do the job, fun fun fun reminds me of the time i did a 4col/ aqueous front and four colour and 27spot colours plus aqueous back for the huge amount of 350 sheets

Paul

P.S next time i might dust the sheets with another pass but i would like to avoid if possible