Urgent! Advice needed on banding issues on litho print

[richardmilne]

Hello all! I really hope someone can help!

I'm working on some folders that are being printed on a litho press in CMYK @ 300DPI. The artwork has a gradient on the background that goes from a deep purple to a light blue. I'd give the exact values and where the steps are but I don't have the artwork to hand. Yesterday the printer gave us a call to say the litho press had put our run on hold because they were worried about banding on said gradient (fair play to them as they could have run it anyway!)

I modified the artwork by applying a blur to the gradient and overlaying a 50% grey with 9% noise. On screen this got rid of the banding, but we got another call today to say that there's still banding according to the RIP preview but just on the magenta channel. I'm worried that adding more noise will degrade the overall quality of the image, or might not even produce any better results.

Can anyone suggest any further modifications I can make to the artwork to get rid of the banding? Time really is an issue! The only thing I can think of is increasing the DPI to 600, but there's a lot of raster images in the artwork that I'm not happy about scaling up.

Please someone help!

[Boss Hog]

What does your printer advise?

[richardmilne]

Spoke to him a few minutes ago, suggested the same thing (add noise) but also applying a motion blur to the noise in the same direction as the gradient to just break it up a bit more. This seems to have solved my problem on all channels .... yay!

Only problem is it's been delayed by 2 days now, but I've learned my lesson!