The ammonia is the principal ingredient that dissolves the standard
Epson dye and resin inks. The reason ammoniated window cleaners are
typically recommended is they also contain glycol which is one of the
solvents used in most inkjet inks (it retards drying) and the ammonia
concentration is just about right for most applications.
Depending upon which printer and ink you are using, the ammonia will be
more or less important. With the pigmented inks it is relatively
critical in dissolving the resins. In the dye inks it helps to control
the pH of the cleaning fluid and does work on the ink solids involved in
a clog, but in a pinch water will sometimes work.
As someone else mentioned, you can smell ammonia, even at the
concentration used in window cleaners. If you cannot find an ammoniated
cleaner, see if you can locate non-sudsy household ammonia and mix it 1
part ammonia to 10 parts water.
Someone else mentioned isopropylene, or isopropyl or rubbing alcohol.
This is mainly a wetting agent, and although it does help to dissolve
some of the inks, it is not the principal active ingredient in the
cleaner. It helps to get the fluids to flow into the nooks and crannies
of the head, and it also helps to dry out the cleaner more rapidly
because it accelerates the rate of evaporation.
Do not use the thick pink Windowlene with inkjet heads.
Art