HS-920 Mold Tool Sealer

HS-920  is a polysilazane formulation that contains “no free silicones” and is a VOC exempt, single component, ambient air cure product that applies to the face side of the mold tool.  It soaks deep into the micro-pores, pinholes, and micro-cracks, and the resin system creates a covalent bond allowing it to become virtually part of the mold tool.  It creates no dimensional change to the mold tool as it soaks into the surface pores via an easy wipe-on, soak-in and cure application process.

This very unique VOC-exempt-based nano-ceramic coating is designed to be applied onto the face side of a leaking composite, graphite, or metal mold tool without fear of silicone contamination as it has “no free silicones” within in.  It can soak into the cracks or pinholes that are allowing vacuum leakage.  Being a nano-ceramic product, it will fill even the smallest of pinholes or cracks, and harden and permanently seal them even when used at elevated cure temperatures.  Physical tolerances are not changed as the product saturates into the surface and/or crack and pinholes.  Any excess is simply wiped off the mold tool face.

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HS-920 Properties


Color Clear
Viscosity 16-18 sec. #2 Zahn
Percent of Solids 18%
Odor (liquid) Slight Solvent
Odor (cured) None
V.O.C. Exempt per CFR 51.100/regulation 8
RoHS Compliant
REACH Compliant
Halogens None
Thermal Stability (cured) 1200+ degrees F (648.8 degrees C)
Conical Bond (1/8 inch mandrel) Passed (ASTM D522-93a)
Cross cut adhesion 5B (ASTM D3359)
Coefficient of Friction 0.03 microns (ASTM D2047)
Specific Gravity 0.889 (ASTM D891-09)
Pencil Hardness 8h (ASTM D3363)
Average applied dry film thickness 2 to 5 microns
Est. Coverage Rate @ 3 microns 4200 sq ft / gal
Transfer to surrounding material Zero (0) transfer of contaminates
Dry to Touch (time @ ambient) 15-25 minutes (average)
Ambient cure (full properties) 5 days