Date: Fri Jan 08 1999 - 15:20:28 CST
I am not aware of any "water-based" cleaners being used by lithographic
printers to clean ink and debris off of press components. There are water
miscible cleaners that are used and the purpose of the water is to remove
paper debris. In some instances, press operators will clean the blanket with
water mixed with a very small amount of solvent and this practice has been
conducted for decades. There does not appear to be any unusual corrosion
resulting from this practice.
A quick answer to the question regarding what is the best cleaner for inks is
that there is no one best cleaner for all situations. In selecting cleaning
solutions with characteristics that are more environmentally beneficial, it is
important to be aware of several critical factors. First and foremost, you
need to consider the area of the press to be cleaned. For example, cleaning
ink rollers versus and impression cylinder poses different challenges. Deep
cleaning ink rollers versus everyday wash ups for color changes also presents
different challenges. In cleaning inks off various press components, the type
of ink also influences the choice of cleaning solution. Sheetfed offset
lithographic inks are typically the most difficult to remove because they are
complex and very viscous while newsinks are the easier because they are
composed principally of pigment and oil with very little other additives.
Another complicating factor for blanket washing is the method of cleaning -
hand or automatic blanket washing.
The other important factor is the approach to take towards cleaning solutions
- low VOC or low vapor pressure. Each of the different types of washes posses
their own advantages and disadvantages. Many of the low VOC washes have
recently used vegetable oils or vegetable oil derivatives to reduce the VOC
content. These types of washes have met with limited success as hand washes,
but have produced excellent results in several automatic blanket wash systems.
However, some printers have used these washes as hand washes with acceptable
results. Low vapor pressure washes, those with less than 10 mm Hg at 68oF,
have been used with good results by printers. While they are considered 100%
VOC, they result in lower VOC emissions because they do not readily evaporate.
Regardless of which wash is chosen, it is important to understand that the
press operators should be involved in the new wash evaluation program. Many of
these washes require changes in work practices and will require time for the
operators to adjust to the new cleaner. Some of the washes require additional
time and effort to get them to properly work. Some leave films that require
additional effort to remove.
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