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Finishing & Preparing the Master Plug
for Mold Making
Primer Coat & Surfacing
33. Wash the master plug in warm water. If you have a blow-down tool for your air compressor; blow any free water off the master plug. This will also remove water and fine dust from any pin holes on the master plug surface.
34. Fill one small air brush jar (supplied in your Paasche VL Set) ¾ full of well stirred, polyester, primer/surfacer. Add 20% by volume of reducer (lacquer thinner), and 3 to 5 drops of MEKP Catalyst (supplied with your Primer). Screw on a “non-tool” lid (supplied in your Paasche VL Set). Shake vigorously for a few seconds. This will blend all ingredients together. Time becomes critical here. Now you have about fifteen minutes to spray (apply) the primer to the master plug body before it begins to gel (become too thick to spray).
35. First apply a light “tack” coat of the primer to the master plug surface. Allow one minute for the tack coat to air-out. Continue to coat the master plug body with primer until the master plug body is completely coated. Use the mounting block to turn the master plug while applying three to six even coats of primer. Let dry approximately one minute between coats. After the last coat is dry, let it stand for at least one hour before handling. Fig. 26.
NOTE: After the Primer/surfacer has dried (cured) completely; small dimples (pin holes) in the on the surface of the master plug body may re-appear. There may also be some small sanding scratches left over from shaping the master plug. Fig. 27. Instructions on the following pages will demonstrate how to accomplish a glass like finish to your master plug before continuing to Mold Making.
Always remember: The master plug you make a mold of will always produce exactly the same part; Pin holes, scratches, & all.
Never use plastic or foam containers to mix primer. The solvents will melt the container. Use paper or metal mixing containers only.
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