Re: Can ink really boil?? Oh yes- but what does boil mean?

[Gary Schnabl <badBadger@badBadger.com>]

Not having yet refilled my cartridges, I accept what you say about the foaming
of the ink in the chamber as the pressure is reduced in the presence of residual
air. I received my bulk ink and blank cartridges three days ago and am now
gathering the syringes and other supplies. I have had similar experiences with
foaming over the years, so what you say makes sense. However, you are a bit too
loose in your terminology.

Boiling and blowing bubbles are two different physical concepts. Boiling is not
the same as deairing. When water boils, it is water vapor as a result of a
change of phase of the water, not air, that is released to the system. Boiling
occurs when the vapor pressure approaches the absolute pressure of the chamber.
Or, to put it another way, the pressure of the chamber is reduced and approaches
the vapor pressure of the ink. Evaporation can also occur, but this needs a
longer time interval to be significant.

Bubbles are indeed related to surface tension. A kid blowing bubbles is not
experiencing boiling of the soap solution. The bubble itself is a product of its
surface tension and it needn't adhere to anything such as a sponge to exist.
What you physically have in the cartridge are three phases: liquid ink, air, and
ink vapor (dependent on vapor pressure of the ink, the chamber pressure, and the
temperature). The ink vapor is gaseous and is probably colorless.

Since you are performing these tests, at what level (% of cartridge void volume)
of evacuation does this foaming occur?

Gary

TMorris862@aol.com wrote:

>  And if ink boils ( deairs) in the cartrigde guess what the sponge will trap
> these fine bubbles!!  Do the words surrface tension mean anything? Once the
> bubble attach to a surface
>  ( sponge) they tend to stay there!
>
> I got some refills with nothing but fine foam in the outlet ink flow  and it
> took a lot of flushing to get the foam out! It really happened guys!! No
> guessing on my part!

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