Finishing Precision Board using FSC-88 WB (Waterbased primer/filler)

1. Sand any saw marks, heavy texture, or roughness from surface to be primed. Use 120 grit sandpaper.
   
2. For deep cuts or abrasions, pretreat by spot priming with FSC-88 WB, or in extreme cases FSC-360 WB repair filler. Allow to dry and lightly sand before continuing. To make FSC-88 WB a thicker consistency for use as putty, pour a small quantity on cardboard and let set until desired thickness occurs.
   
3. Apply light coat of FSC-88 WB by brush, roller, or spray gun. When applying by brush or roller, work in the first coat to wet out the cells. Allow to dry to tack free - about 15 minutes. Recoat as soon as surface is tack free. See FSC-88 WB Product Data Sheet for spraying details. If slower drying of FSC-88 WB is desired, especially when applying by roller, add about 5% water. Do not sand between coats. Do not use sponge roller as it will not leave enough FSC-88 WB on the surface. Important - second coat should be applied thick enough to create a smooth, creamy surface.
   
4. Apply a second coat heavier than the first coat. Do not allow it to run. Allow to completely dry. Remember, all sanding must take place in the FSC-88 WB before getting back to the original Precision Board Surface. Since Precision Board is made of millions of tiny cells it is not possible to sand PB smooth.
   
   In areas of detail, i.e., relief cuts, vertical sides, and other hard to reach surfaces, allow the FSC-88 WB to dry just a little longer than tack free. Use a medium stiff brush wet with water to gently smooth out and polish the primer/filler. With a little practice you will be able to use this technique to eliminate all sanding of these hard to reach areas. Let dry overnight before continuing.
   
5. Sanding of the primed surface can begin when the FSC-88 WB does not ball up on the sandpaper. If it does, allow the piece to dry longer before continuing. Begin sanding using 120 grit sandpaper and finish with 220 to 320.
   
   Faster sanding can be accomplished using 320 wet/dry sandpaper and wet sanding with water. Keep the surface totally wet and use minimal pressure as this method cuts very quickly. Let dry a minimum of 12 hours before proceeding.
   
6. Prior to painting, lightly sand small areas with 220 grit sandpaper to be certain FSC-88 WB is completely dry. It is totally dry and ready for paint when no balling or streaking occurs on the sandpaper. If it does, let dry until it no longer occurs. Applying paint over even slightly wet primer can result in blisters under the paint when the sign is placed outdoors.
   
7. For faster drying, after the FSC-88 WB has been applied, use shop fan to blow across surface. Turn fan off during application. Frictional heating of the air rolling over the surface will expedite drying. Do not place in direct sunlight as it might dry too quickly causing blistering in the primer.
   
8. When sanding is complete, wipe with tack rag and proceed with top coat system.
   
   Clean up using warm, soapy water. Thoroughly clean spray gun, connecting lines, and tip.