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UltraSandable gelcoat

UltraSandable 1-SP sandable gelcoat for resin transfer molding (RTM) applications is an ideal surface for all secondary finishing operations. A high level of neopentyl glycol (NPG) and other high-quality ingredients, together with perfected manufacturing techniques and rigid quality standards, optimize every feature you look for in a sandable gelcoat:

  • Shelf stability
  • Easy application
  • Excellent sandability
  • Excellent paint adhesion
  • Crack resistance
  • Chemical resistance
  • Long-term durability

Sandable gelcoats are available in black and gray as standard. Please consult Ferro for product numbers, which vary by application. Custom colors are available on special order.

Uncured gelcoat properties
(All properties based on 1.5 percent MEKP)

  • Gel time @77ºF to your specifications (within parameters required to maintain product integrity)
  • Gel to peak.................15-20 minutes
  • Viscosity @77ºF (LVF #4 @60 rpm)........2,300-2,900 cps
  • Thix index (6/60)...........5.0-6.0
  • Weight per gallon...........9.8-10.8 lbs.
  • Stability @150ºF...........5 days minimum
  • Hegman grind..............5 minimum
  • Film cure @77ºF..........40-60 minutes
  • Hide @15 mils (wet).....complete
  • Coverage....................approx. 80 sq.ft./gal., sprayed @20 mils (wet)
  • Patchability..................good (Ferro patch booster recommended)

Cured gelcoat properties

  • Tensile test (ASTM D638 IV):
    Elongation..................2.8-3.5 percent
    Tensile strength.............6000-8500 psi
    Modulus elast..............0.25-0.33 x 106 psi
  • Coefficient of linear expansion...................5.1 x 10-5 in./in.ºC
  • Linear polymerization shrinkage
    (ASTM 2566)...............0.0165-0.0180 in./in.ºC
  • Barcol hardness............38-45, in 1/8" gelcoat casting

Cured composite properties
(Gelcoat with laminate)

THREE-POINT BEND TEST (ASTM D790) WITH GENERAL-PURPOSE (GP) RESIN WITH DICYCLOPENTA- DEINE (DCPD) MODIFIED RESIN
PERCENT ELONGATION 1.7 - 2.2 1.2 - 1.7
TENSILE STRENGTH (PSI) 12,000 - 16,000 10,000 - 13,000
MODULUS OF ELASTICITY (PSI) .80 - 1.0 X 106 .80 - 1.0 X 106

Blister resistance:
(Boiling water exposure test, with panels evaluated according to ANSI procedures)
@ 100 hrs..........................excellent
@ 200 hrs..........................fair - good

Typical applications

All resin transfer molding (RTM) applications.