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NEUTRALIZATION OF STATIC
ELECTRICITY Charges of static electricity accumulate on the surfaces of
Chemcast® GP acrylic plastic during processing, and cause uneven
paint deposition and paint crawling. These static charges are
most common under dry winter atmospheric conditions of low
relative humidity. Conditions of high relative humidity,
conversely, reduce the problems of static charges. At 70 percent
relative humidity, for example, there is no problem in painting
except for the possibility of moisture condensation on the
surface of the Chemcast® GP. Antistatic solutions affect paint
adhesion and can not be used on a Chemcast® GP surface which
will be painted. There are a number of ways to eliminate static charges on the
Chemcast® GP surface. One effective method is to wipe the side
that is not to be painted with a mixture of 10 parts isopropyl
alcohol in 90 parts water, applied with a well wrung out chamois
to minimize water spotting on drying. If the surface
to be painted is wiped with the alcohol water solution,
the moisture must be removed from that surface by blowing with a
dry air gun. Care must be taken, however, since excessive
blowing will generate a new static charge. A metal window screen placed near the surface not to be
painted will also reduce the static charge. For best results, the
screen should be grounded. Silk screen tables can be covered with grounded conductive
rubber sheeting or wire glass. The screen frame can also be
grounded by strips of copper. After the plastic sheet is placed
on the conductive material, a tinsel bar passed across the upper
surface but not in contact with it will dissipate the charge. Wiping the surface to be painted with a clean flannel cloth
dampened with 99 percent isopropyl alcohol may also remove the
static charge. If the flat sheets will be heated after screening,
the alcohol will not cause crazing. Strong atmospheric ionization
will also remove static charges from Chemcast® GP. Low voltage
induction equipment and ionizing air guns are available from a
number of sources. The manufacturer of the equipment will give
specific recommendations for static elimination. CAUTION: The air guns contain radioactive materials which emit
alpha particles. Under no circumstances should they be
disassembled. The guns should be returned directly to the
manufacturer for servicing |
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Copyright © Plastiglas de Mexico 1999
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