Newspaper and Cleaning Glass
Date: September 2006
Why are newspapers very effective in cleaning
glasses/mirrors? Why does the ink from newspapers not stain the
Some newspapers will cause glasses and mirrors to smear. There
are several factors that play a role:
1. Newspaper (in the trade referred to as "newsprint") contains no
solid components like calcium carbonate or silica, like higher
quality paper. These minerals can scratch the glass, which can be
confused with smearing.
2. Older newspapers were printed (and many still are) with oil based inks --
basically a cheap mineral oil. These too will smear or stain a
window or mirror if a solvent or detergent is used to "clean" the surface.
3. Now the trend in printing inks for newspapers is to use water
based inks. This allows newer and different types of pigments to be
used too. These papers don't contain the oil of the older
conventional inks and consequently are less likely to stain or smear
a mirror or window.
There are two tests to tell which type of paper/ink combination
is being used:
1. Hold the newspaper (or magazine for that matter) between your
thumb and index finger for a minute or so. If your thumb/finger
stains, you are using the old type of ink. The newer water based
inks do not transfer on to your finger.
2. A related test is to gently rub the newspaper with a piece of
typing paper. The friction will cause the older paper/ink
combination to stain the typing paper. The newer water based systems
are much more resistant to this type of test.
Newspapers are good at cleaning glass because the paper leaves very
little lint. Compared to paper towels, news print is much more
rigid and hence the fibers will not individually separate like they
will from a paper towel. This is the source of the lint. The ink
does not come off for two reasons, one you are wiping a mirror or
glass, which is a highly polished surface, so there is nothing for
the dried ink to stick to. Second, upon wetting the news print with
liquid, the ink becomes infused in the fibers of the
newsprint. Think of ink as nothing more than a stain. It is hard to
stain windows with ink, yet easy to stain paper. Glass does not
absorb ink, while paper will. And so all of the dirt on the window
or mirror will be absorbed into the news print.
To think of this more on a molecular level, the paper is nothing
more than long interlinked strands of atoms with a flexible
backbone. Glass however, is a highly crystalline solid that is
hydrophobic (repels water). The molecular properties of each give
the unique properties in absorbing stains.
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Update: June 2012