Simple guide 3 processes to polyester resin painting

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Paint Polyester Resins
How to
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• Whether a newly cast figurine or freshly glassed
  boat hull, the silky smooth texture of cured
  polyester resin presents a distinctively
  difficult painting challenge. Most paints simply
  cannot adhere to the slick surface. Paint pools
  and if it does dry, it often chips and flakes
  with the slightest bump. By carefully following a
  step-by-step process that includes thoroughly
  cleaning, sanding, priming, and applying both a
  basecoat and topcoat, crafters and boaters can
  overcome the polyester painting problem and
  enhance the overall look of their resin projects.

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Polyester Resin Properties

• Unsaturated polyester resins starts as a liquid
  and becomes completely solid with the addition of
  a catalyst hardener. Most marine and figurine
  resins contain a small amount of wax. This rises
  to the surface after application and forms an
  airtight seal that allows the resin to cure.
  Without this seal, the resin does not set
  completely and results in tacky surface. In this
  case, the resin needs some sort of wax-based
  topcoat. The average product working time for
  polyester resin depends on environmental factors
  like temperature and humidity, but typically
  lasts up to 30 minutes. It cures in 6 to 8 hours.

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Polyester Resin Painting Process

• To begin this project, first assemble the
  necessary supplies. For prepping the resin
  surface, gather a heavy cleaner like acetone or
  denatured alcohol and 180-grit wet use sandpaper.
  Choose a quality spray primer formulated for use
  on resins, plastics, or metals for the priming
  step. The materials for painting depend on the
  project Select either a weather resistant marine
  paint for watercraft or a gesso basecoat and
  acrylic topcoat for crafts. Also stock up on
  generally useful supplies like lint-free rags and
  paper towels as well as safety gear like rubber
  gloves, protective eyewear, and a disposable dust
  mask.

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• 1. Prep Surface
• When refinishing older polyester resin, first
  inspect the surface area for damage. Use
  all-purpose fiberglass filler to repair and seal
  cracks, nicks, or other irregularities. Let all
  repairs cure completely. Next, thoroughly wash
  the surface with a wax-removing, non-residue
  cleaning solvent. Repeat cleaning on new resin to
  remove all of fresh sealing wax. Finally, sand
  the surface with 180-grit wet sandpaper.
  Continually wet the sanding area with water from
  a spray bottle and move in smooth, even circles.
  Stop when the resin surface looks cloudy. Wipe
  the sanding residue away or blow it off with a
  compressed air duster.
• 2. Prime
• Prepping the smooth resin surface improves paint
  adhesion later, but not nearly as well as several
  coats of primer do. Double check that the surface
  is free of grit and completely dried before
  proceeding. Equip a can of quality primer
  PlastiKote Sandable Primer or Krylon ColorMaster
  Plastic Primer works well with a reusable
  snap-on spray paint holder. This handy tool
  reduces finger fatigue and makes even painting
  much easier. Holding the can about 8 inches from
  the surface, spray the first layer of primer
  using quick, evenly spaced strokes. Opt for finer
  coverage over thick to minimize drips and drying
  time. Let the first coat dry for about 10 minutes
  before applying a second layer.

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• 3. Paint
• Up to this point crafters and boaters can utilize
  the same steps for working with polyester resin,
  but forthcoming painting techniques differ. When
  working on watercraft, pour marine paint into a
  standard painter's tray and use a snort nap
  roller for application. Paint three to four
  layers and consider adding an additional layer
  around the water line and other spots where the
  boat suffers the most wear.
• Crafters should first apply a gesso basecoat to
  their resin cast or composite. The product is
  typically used to prep canvases before painting,
  but when used on primed polyester resin it
  provides an additional adhesion layer that paint
  easily sticks to. Paint a single thin base coat
  of gesso onto the cast with a synthetic bristle
  brush. The product goes on thick, so keep a
  clean, damp brush nearby to sweep away any gesso
  globs before they dry. When dry, paint over the
  base coat with standard acrylic paints.

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