Layer void impregnation

Layer void impregnation, application of discrete isolated sections of consolidant where laminants have lost adhesion. Lac-querware surfaces separated from their ground or dissociated laminates can often be stabilized with this method. Judicious use of molten waxes or thermosetting adhesives is generally successful because of their unique physical and mechanical properties. 

Metal substrates coated with a layer of controlled porosity and impregnated with catalyti-cally active material—Fig. 4—offer high surface area and high void fraction and are therefore particularly attractive for applications where pressure drop is a parameter of primary significance. 

The assembled composite may be cured at room temperature or at elevated temperatures for faster cycles. This procedure, which was originally called contact molding, may be upgraded by the application of a vacuum or pressure bag placed over a Cellophane film on the final layer to reduce void formation in the composite. The laminate may also be built up by a spray-up process in which a mixture of chopped glass strands and catalysed resin is sprayed on the gel coat instead of resin-impregnated mat. In any case, the inner surface will be less smooth than the first layer formed by the gel coat. Tanks, boats and pipe may be fabricated by this technique. 

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