OLDER HP Presentation about Piezo vs. Thermal...still relevant

This presentation by HP is a bit dated however it will still illustrate the key differences between the Epson printhead and HP/Canon type thermal heads. While it certainly is slanted towards HP as being superior, the ONE thing to get out of this is the air in the printhead issue and how it gets in there.
Many don't understand what the typical Epson clog is all about. Most times it is not a physical clog but the same issue that has dogged piezo printheads. Slides 29 &30 This will better illustrate what happens. Once air is inside the piezo nozzle chamber, it loses forceful pumping action. Remote areas inside the piezo head that has cuumulated bubbles is what causes the sometimes off behavior of head cleaning in one color then causes "clogs" in another. The head cleaning drags the air bubbles into the nozzle chamber.

1998 !
On page 11 my first HP Deskjet.
It was probably used with caution, but I do not remember high ink costs or clogging.

Even if on HP/Canon printers the air bubbles are less important, it could explain why you sometimes better stop fiddling with the printer and just print.

Once air enters the nozzle chamber...it is like air in your auto brakeline. No ink exits even when the printer prints or pumps. At this time you think you have a clog.