Windmill ghosting

I’m having bad ghosting issues right now. Running PMS 389 (light green) on uncoated label stock. I’ve tried adjusting inking, putting spray tack on the rails and bearers and moving the rollers in and out and I can’t get rid of this.

The attached pics show 3 successive prints. It’s different every time. I’ve blown out the contrast so you can see it better. The plate image is about 4 inches tall.

Any help?

image: image3.jpeg


Log in to reply   8 replies so far

Tried rotating the plate but still got ghosting. I just have no clue what to adjust.

Are you using a rider roller?

I have it on now. The ghosting changed but it’s still there. Instead of it being a darker ghost, it’s now a lighter section.

image: image.jpeg


I can’t tell exactly from the picture, I would suggest that your using a transparent white as part of this ink color.
It really looks like what transparent white does. Try using an opaque white.

I bet it will work much better.

Theo Bell

Clearly you have a mechanical ghost. In the first image you can see that the darker inked area in the design is the exact replica of the unprinted gap between segments.
Your green color bar at the bottom of the photo shows that your rollers are printing consistently. The bar is solid with no apparent ghosting. This type of ghost is caused by the lack of ink being removed from the rollers as it passes over that gap. It then deposits that excess on your paper when the roller comes around. Rotating the form will probably not solve it. You can try to rotate the form 90 degrees, it might help or may just make the ghost reappear in a different way. If the gap between the print area on the form were equal to the width of the image you may have better luck.
Pretty sure if you were printing your image one up you wouldn’t see any ghosting.
A common cure is often adding “take up bars” to the image area. These are images that resemble the “white gap” so that they strip off the excess ink that the rollers want to be laying down.
Try looking at the paper company sappi’s website. Re:ghosting
They should have some detailed info about mechanical ghosts as well as chemical ghost which is a whole “nother” topic which is more related to offset chemistry/physics than letterpress. (While your there see if the Flo channel videos are there, if not check them out on you tube- great fun for printers.)
Good luck

The ink was pre-mixed, so I didn’t specify trans. vs. opaque white. I’ll think about that for next time, though.

Thanks for your suggestions. I did rotate the form 90 degrees but the ghosting just reappeared in the same place.

In the end, I made lots of little adjustments to the rider roller and the rail heights, and found that after just running it for a little bit, the ink settled down and printed cleanly.

My next run will be Red 032, so hopefully this won’t be as much an issue. Definitely no transparent white in that.

Thanks, all!

Hmm, do you think it was a plate issue then, like the plate wasn’t loading with ink or you hadn’t had enough ink on the rollers yet?

It did take me a while to get up to color, so maybe it was just a matter of getting that set. I did have to have the ink flow set to 6 or 7 so it would keep color as it ran. I just didn’t recall such bad ghosting the last time I ran the job.

I don’t think it was the plate, as it eventually ran fine, plsu I’ve never had trouble with plates from my platemakers.