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RE MASKING The masking paper used on CHEMCAST® GP sheet
will retack and may be replaced if desired. The adhesive bonds
firmly to itself, however, so the coated sides of the masking
paper must not be allowed to contact each other. The masking
paper can be rolled up in loose tubes and stored on pegs in a
clean, dry area. Take care to avoid contaminating the masking
paper with dirt to keep from scratching the CHEMCAST® GP when
the masking paper is reapplied. Prepared masking papers are available from a
number of sources and may be used for re masking. Before using a
different masking paper, however, check the adhesive to be sure
it will not attack the CHEMCAST® GP. PROTECTIVE COATINGS Masking compounds that can be sprayed on the
CHEMCAST® GP and later peeled off may be used, especially when
formed parts are to be masked. The spray masking compounds should not have a
harmful chemical action on the CHEMCAST® GP. Some masking
compounds may be used indoors for periods as long as 12 months.
In general, no masking compound should be used on parts that will
be stored outdoors for more than two months. When spray masking compounds are used, the
coating must be at least 35 mils thick. The film should also be
uniform and free from runs and other imperfections. If the film
is too thin, it may be difficult to remove. To remove spray masking from CHEMCAST® GP,
peel it off or lift a corner of the film and blow a jet of
compressed air under it. If the film is hard to remove because it
was applied too thin, apply a fresh coating of the masking
compound, let it dry, then remove it. In some pallets, it might
be necessary to apply a layer of cheesecloth over the fresh spray
coating, let the coating dry, and then apply another coating and
let it dry before attempting removal. The cheesecloth reinforces
the spray coating and makes it easier to remove. If the film has
deteriorated because it has been stored outdoors, soaking the
coated part in cold water for 24 to 48 hours may help to soften
the film. Stripping compounds supplied by the manufacturers of
the spray masking compounds may also be used if they will not
craze the CHEMCAST® GP. Protective spray masking coatings must be
removed from parts made of CHEMCAST® GP before the parts are
annealed. If the coatings are not removed before annealing,
optical distortions may appear in the annealed part in areas in
which the thickness or surface of the coating is irregular. |
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Copyright © Plastiglas de Mexico 1999
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