Color Banding - HP9000

[nickmiser91]

Does anyone know what could cause this sort of color banding? It happens when printing a solid spot color, there will be gradient of color that bands horizontally through a piece, sometimes multiple times.

 

[danno]

It looks like you are running in a 4 pass mode. Have you tried running in 8 pass? Also look at putting a pause between passes. Usually I haven't seen that unless the complete width of the media is printed as a solid colour.

 

[nickmiser91]

It looks like you are running in a 4 pass mode. Have you tried running in 8 pass? Also look at putting a pause between passes. Usually I haven't seen that unless the complete width of the media is printed as a solid colour.

This was run at 8 pass. I've noticed this before and at times it can be gotten away with if it was a larger output that was made to be viewed at a distance, everything and everyone looks better at a distance. This piece however is going to be die-cut lettering and is pretty noticeable. I don't think it will fly for the customer but if it does, it does. If not I could try 16 pass perhaps, don't think that will solve the problem.

 

[danno]

The only other thing that comes to mind would be an air leak or ink restriction. Have you stopped the machine when this happens and completed a nozzle print?

 

[greysquirrel]

OEM or 3rd party ink? How does the nozzle print look? Are you running color bars with your print? This forces ink fro all of the nozzles every pass...have you run an integrity test to see if caps are working properly? (Fill cap then manually move carriage to see if caps are full)
if starvation, dampers and all rings at every fitting from sub tank to print head should be replaced...over time the rubber ring dries out and tightens around the hose causing a warm choking sensation commonly referred to as ink starvation...