Discussion Factors Affecting Print Quality in UV Printers.

[siphon56]

Hello everyone! I have a Roland LG 300 UV printer and have been using it for a while. Lately, I've noticed an issue when printing black and white designs: some spots appear faded compared to others. This doesn't happen with color prints; they come out perfectly fine. If it were a printhead clog, it should affect all prints, but it only happens with black and white designs. Could it be related to the black and white design, humidity, temperature, or something else? Any ideas on what might be causing this? In the image below you can see those specific icons on the corner is bit faded in compared to other icons.

 

[GaSouthpaw]

A possible culprit that I've encountered is that the media is somehow contaminated. Would run into that occasionally with wallcover and less often with vinyl (though once had a batch of 150 or so rolls plus of 3M that had manufacturing issue that they took forever to admit to- even though we were printing the media for them). The contamination (light printing) was always much more noticeable on darker prints (like black and white).
Not saying for certain that's you're problem, but it's something to look for- particularly if your nozzle tests show everything firing correctly.

 

[SE SignSupply]

Looks like the material might not be laying flat on the platen in the impacted areas, this would throw your bi-directional alignments off (m-gap adjustment in your machine).

To test this theory, print in Uni-Directional mode. If the problem goes away, figure out why your media is buckling while printing.

 

[TEN]

White ink is very prone to being problematic. Print nozzle tests on black vinyl or a substrate that you can see the white nozzle pattern on. Look for issues such as: nozzle deflections, overspray, etc. Each color, white and clear will have its own channel or a section of a print head or many printers will have seperate print heads for the different channels. You can totally have issues with just the white and all of the other colors will be printing fine. Talk to your dealer or Roland tech.