570 Greys going Purple long prints

[lknmedia]

When printing long/large grey prints they are slowly going to a purple hue. I'm thinking C or LC running out? C/K printheads new, LC/LM at about 3k. Any idea on how to diagnose? I don't really just want to blindly change parts.

 

[balstestrat]

Replace the light ph.

 

[Stacey K]

Something you can try for free...print some 3" squares each would have the following...100% Cyan - 100% yellow - 100% Magenta - 100% black - 50% Cyan, 50% Magenta, 15% Cyan, 15% Magenta.
See how they look, you should be able to tell if any of your inks or your heads are bad depending on how the color comes out.

 

[Ron at Forest Litho]

Check your file - put it in photoshop and see what makes up the gray. If someone converted it from RGB to CMYK the "gray" may be equal parts of CMY. That screwed me up 30 years ago. Too may people use RGB programs and then convert! For example, a simple 20% black if converted from RGB might be 15% C, 15%M, 15%Y. and they look gray as long as your printer is perfectly balanced. But if you decide that the reds in the graphic need to be redder and you push your magenta a little, all of a sudden that former RGB grayscales are getting toned magenta. If they were actually a % of black only it wouldn't happen.

 

[netsol]

Check your file - put it in photoshop and see what makes up the gray. If someone converted it from RGB to CMYK the "gray" may be equal parts of CMY. That screwed me up 30 years ago. Too may people use RGB programs and then convert! For example, a simple 20% black if converted from RGB might be 15% C, 15%M, 15%Y. and they look gray as long as your printer is perfectly balanced. But if you decide that the reds in the graphic need to be redder and you push your magenta a little, all of a sudden that former RGB grayscales are getting toned magenta. If they were actually a % of black only it wouldn't happen.

That wouldn’t make it slowly go purple as it prints

 

[Ron at Forest Litho]

That wouldn’t make it slowly go purple as it prints

As I said, it would if your printers colors are off balance. OR if you pushed a color to customize the output . As I said. Like to match a red that customer wanted.

 

[netsol]

sure sounds like ink starvation to me ( and i have been doing this since the 1980's)