HP Latex ink is a fundamentally different chemistry than any solvent ink-set. With HP Latex ink in the L250 and L260 machines, the evaporation and curing are entirely environmentally induced reactions that must take place inside of the printer. The ink-set used in the Latex 300 series are a bit different from the previous machines in that they added a pre-treatment to the ink-set (Optimizer).
The addition of heat to the environment is essential for the L260. Heat is applied in two areas of the printer, in the print zone, and in the curing zone. The print heater's job is to evacuate the water content from the ink. The curing heater's job is to melt the latex polymers in the ink into a shell that encases and protects the pigments. If either heater does not do it's respective job, then print artifacts of various types will result. Wet ink, oily ink (rewetting), coalescence, ink bleed, etc. If too much heat is applied for the specific media, other issues can result, depending on the media. These can include physical deformation, bowing, head (carriage) strikes, size deviations, and more.
In short, not enough heat (or time) = ink issues, too much heat = media issues.
HP has published a chart that describes the recommended minimum pass counts for the various media classes. That chart is attached.
PVC Banner minimum = 8 pass
SAV minimum = 10 pass
Textile minimum = 12 pass
Coated paper minimum = 6 pass
See the attached PDF for more info. The chart is valid for the Latex 2 series (L25 and L26) only. The 300 series have very different pass count minimums and recommendations.
When it comes to drying the ink, there are several things that can be done:
1. Add heat in the print and/or curing zones
2. Give the heaters more time to do their jobs. This can be done by:
a) increase the pass count
b) introduce an inter-pass delay between the passes (this is highly effective)
c) reduce the amount of ink being applied (less ink = easier to dry & cure)
