Digital BW, The Print

1- Jim, Yes Web presses are ugly monsters and we unfortunately had 
some ugly injuries in my department... I hate it...

2- Amonia would only be good to get pH, and the printhead might not 
like it... I would rather use some combination of water/solvent.

3- John, I agree totally with your statement to clean printheads. 
Even though some industrial ink suppliers claim they are getting 
close, I have not seen a pigment ink that does not need some amount 
of solvent to stay in solution. A small amount might be enough (2-3% 
with the newest inks) but you will need some. To re-solubilize 
(=clean off) pigment inks you need more than that though, and you 
also need some water too (high polar strength of water makes alcohol 
or glycol dissolve better). The best solution at home to clean a 
printhead is probably to use medical alcohol (the stuff to clean off 
wounds, which is at 70% ethanol) and cut it with purified water (most 
water sold for drinking should do - stay away from Evian/Dasani 
because of the high mineral content ;-)). Or vodka !!(most vodkas are 
fairly pure 40% ethanol 60% water)...

4- If you are looking for something that evaporates slower, i.e. for 
the cleaning pad, propylene glycol might be the best solution 
(ethylene glycol will evaporate a little faster but is good too). I'm 
not sure how to find it in small quantities (we buy it industrially 
in large quantities). They are both TOXIC by ingestion though! Might 
not be great to use it in a house (children,...). On the other hand, 
they are much less dangerous than bleach (Clorox,...) and on the same 
level than Windex and other cleaning products...

Erik.


--- In DigitalBlackandWhiteThePrint@y..., John Thompson 
<alphajohn@m...> wrote:
> Denatured ethanol (AKA: denatured alcohol) was / is the choice of 
printhead manufacturers / remanufacturers. When they recieve 
alleged "defective" heads due to clogging etc, they use this 
to "cleanse" the jets, typically by total immersion into an 
ultrasonic bath of denatured ethanol cut with purified water 40/60. 
(if memory serves). I have a pdf of a current MSDS sheet on denatured 
ethanol for anyone's review,  just request it off-line. 
> Glad to help, - JT
> 
>  >>  My concern is the possible crossive effects of Windex 
(ammonia) on 
>   >>  the print heads.  Any info on that?
> 
>   >>  Jim
Message: 11
   Date: Thu, 07 Mar 2002 00:05:24 -0000
   From: "jimhayes361" <jimhayes@...>
Subject: Re: Chemistry of Windex, Fantastik, 70%Alcohol

--- In DigitalBlackandWhiteThePrint@y..., "erikhuneker" 
<erik.huneker@p...> wrote:
 Part of 
my 
> background is in flexo printing (the 50" web, 800 ft/min, 8-colors 
> CMYK, $5 million dollar type of machines)

Oh yeah, you mean the web press stuff. Good gosh I at one point 
briefly prepared plates for a 6 color web. Huge monsters. Never ran 
the darn thing though, yikes. I like keeping all my fingers.
 Would the inks be similar then?

 as well as chemistry, 
> amateur photograph and for 3 mths proud owner of a Canon S800 to 
get 
> started in digital printing.


Yes, but the Canon uses different technology, not Piezo but some form 
of thermal I think- the ink would be way less viscous I imagine.

> 
> The inks we use in flexo printing are somewhat similar to the stuff 
> used for inkjets (some solvent, water, carrier and pigments etc...).

like Epson or more like Canon or HP tho...maybe they're all 
reasonable close when it comes to chemical makeup?
 
> In my opinion, you certainly do NOT want to use the clear ink. It 
> contains the carrier(or base) with the solvents but no pigments, 
and 
> that carrier will dry and stick to the pad and to the printhead. 
Not 
> good...

Then the mechanism is if I have a puddle of clear ink base, the 
solvent will evaporate out leaving the carrier which will gunk up. If 
this is the case, if I now take a drop of MIS pigment ink and put a 
puddle down, I'll be left with the carrier and the pigment as gunk. 
Wouldn't this happen if a person did too many cleaning cycles and 
overwhelmed the vacuum pump hooked under the parking pad?
Just thinking out loud...

> 
> Jim, your comments were absolutely correct on acetone, water, 
> solvents evaporating etc...

hhmmm..ok. Looong time ago I studied that stuff.<g> 

 Most solvents that dissolve the 
> base/pigment combination (non-polar) do evaporate.

i.e. water-based solvents.


 Some that do not 
> are oils (as in olive oil, kitchen oils or motor oil). But they do 
> not have a good dissolving power, and if a liquid does not 
evaporate, 
> I am fairly sure that there will be some sticking to the printhead 
> and causing trouble printing.


to make it clear to a gearhead...are you saying I want to put on the 
little parking pad a water-based solvent that will evaporate 
completely, but slowly? Or do I misunderstand?

Since Fantastik is for cleaning kitchen grease, it is then a polar 
solvent? This can't be true, as I can spray it on dried ink and it 
disloves/dilutes it.

> 
> Try to go for the solvents that do evaporate the slowest, and for 
> that the glycols are the best option. Careful not to smell them too 
> much though, some are toxic...

Well, I was thinking the clear Epson base had di-ethylene glycol in 
it. But maybe that's the solvent, and there's also a killer carrier 
mixed in.

If I restricted to Windex, Fantastik, or alcohol, I think I would 
then 
remove alcohol from the list, as I think it evaporates faster than 
the 
other two mixtures. I think this may leave me with Fantastik as being 
the better solvent with a slow evaporation rate.

Perhaps you can suggest a glycol that would be relatively safe to 
handle and easy to obtain. Di-ethylene glycol didn't look exactly 
harmless, but what do I know?

> 
> Hope this helped,

Yes it did, although as you see, it raised more questions. Where I 
came from, that was usually a good sign tho<g>.
Jim H.
> Erik.