UMAX Technologies Astra 3400 Operation Manual page 76

Cleaning
Regularly cleaning the object glass will ensure that dirt or smudges will not
reduce the quality of your scanned images. Before you clean the glass, make
sure the scanner is turned off and the power cord is unplugged.
Clean the object glass and document cover with a soft damp cloth and a mild
detergent or alcohol.
Warning: Do not spray the cleaning fluid directly on the
object glass. Spraying the liquid directly on the
glass may cause the liquid to penetrate the seams
around the glass and contaminate the mirrors and
lenses inside the scanner. Please be sure you spray
the liquid on the cleaning cloth and then wipe the
glass clean.
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