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6.1.4
(continued)
Ideally, resin should be so catalyzed that it begins to solidify as soon as
it has been combined with the desired reinforcement and formed into the
desired shape. Since the time required for these operations varies, refer to
the resin manufacturer's data sheet to determine the correct amount of
catalyst (and promoter, if required) for good results. The time required far
solidification to begin is commonly known as the gel time.
Even mildly over catalyzed resin cures in a hard solid rather sooner than
desired, so that the time available for the production of a finished part is
reduced and quality may be lowered. On the other hand undercatalyzed resin may
cure very slowly, if at all, and attempts to use it will result in a prolonged
waste of time and labor.
To lengthen the "pot life" of catalyzed polyester resin, fiber glass
workers recommend the following practices.
1.
Mix only small quantities of resin and catalyst at
a time.
2.
Avoid high ambient (surrounding air)
temperatures.
3.
Keep containers cool, such as by placing
them in ice water.
Here are some suggested safety precautions:
1.
Allow ample ventilation.
2.
Keep away from open flames and sparks.
3.
If promoter is required, add carefully controlled
amounts to the resin first, and then add the
catalyst.
4.
Never mix just promoter and catalyst together - a
violent explosion will result.
6.1.5
Gel Coats
The glossy, opaque, and (usually) colored surface of a fiber glass product is
called the gel coat. Its purpose is to protect the product as well as make it
attractive to the eye. For example, the gel coat covers up protruding surface
SECTION 6
Page 3
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