Streaks on prints

[benoitv]

Hello,


My Riso RP3700 often makes vertical streaks (perpendicular to the printing / feeding direction), especially on light prints.

It does not make it with every drum, but mostly with my blue and black drums, almost always at the same place. It's generally visible in light areas.

at first I thought it could be the TPH, but as it is always on the same spot, and perpendicular to the print direction, it must come from somewhere else. The master doesn't look wrinkled.

Thank you very much for your help!

Benoit

[jermyth]

Check the optics. Have had to replace the scanner sponges to keep dust out on serveral RPs & RNs.

[benoitv]

thanks for your reply. I forgot to mention that I only print from files, never with the scanner so it must have a different origin.

Benoit

[jermyth]

Hum...maybe a ink transfer issue? Any ink leaks on your drums? Check your timing roller, impression roller and exit belts for ink.

[benoitv]

Hello,

I did check, there is no sign of ink leak. the streaks are very thin and white, like lines. That makes me think there is a problem on the master itself, but I don't get why it makes it only on one drum and ocasionnaly on the other one, nor why these lines are always on the same location!

Benoit

[benoitv]

Problem solved!

Strangely enough, it was coming from a glitch with the screening. If I use a "classic" screening the lines disappear!

Benoit

[RRodgers]

Problem solved!

Strangely enough, it was coming from a glitch with the screening. If I use a "classic" screening the lines disappear!

Benoit

I was going to recommend to try an internal print (the one to get the ink out of the drum would probably work) but I'm glad you got it sorted.

[johnrheznik]

hello there try to focus on the said drum maybe the ink squeegee have foreign objects stacks or your ink motor supply is not working properly.