RBC-3425 Resin


RBC-3425 is a filled, low viscosity casting epoxy resin which can be used for duplicating any size casting when used with the appropriate epoxy hardener. RBC-3425 when mixed with AB-312 hardener yields castings with excellent high temperature properties. Because these are 100% solids systems there is very little shrinkage.


Mixed Viscosity @ 25oC, cps: 950
Shelf Life, (closed Container @ 25oC): 12 months


Color: Tan
Specific Gravity @ 25oC: 1.40
Hardness, Shore D: 87
Linear Shrinkage, in./in.: 0.003
Moisture Absorption 10 Days @ 25oC, %: 0.20
Izod Impact Strength, ft. lbs./in. of notch: 0.31
Tensile Strength @ 25oC, psi: 7,100
Compressive Strength @ 25oC, psi: 15,800


Thermal Conductivity, cal/sec/cm2/oC/cm X 10-4: 8.0
Thermal Stability, 1000 Hrs. @ 175oC, % Wt. Loss: 0.50
Coefficient of Thermal Expansion, in./in./oC X 10-6: 39
Heat Distortion Temperature, oC: 55
Operating Temperature Range, oC: -55 to 155


Volume Resistivity @ 25oC, ohm-cm: 8×1016
Dielectric Strength, volts/mil: 475
Dielectric Constant @ 25oC, 100 KC: 4.1
Dissipation Factor @ 25oC, 100 KC: 0.021

(Note: The above properties are typical of a system cured with hardener #B-31.)


AB-85: A fast set room temperature cure hardener used to make small castings. Can use heat for very fast cures. 

AB-98: A medium set room temperature cure hardener with a good working time (90 minutes). Can be used to make small to medium size castings. Can also use heat for faster cures.

AB-312: A medium set room temperature or heat cure system that can withstand high temperatures (300oF). Can also use heat for faster cures.

B-31: A slow set heat cure system with a long working time (3 hours) offering excellent air release for pieces with undercuts.


Weigh the desired amount of #3425 Resin into a clean container and combine with recommended hardener in one of the ratios shown below.

Hardener Parts by Weight
per 100 pts. Resin
Pot Life 
100 grams @ 25oC
AB-85 25 10-15 minutes
AB-98 25 90 minutes
AB-312 17 2 hours
B-31 25 3 hours


Hardener Cure @ 25oC Cure @ 65oC Cure @ 100oC
AB-85 12 hours 30 minutes
AB-98 24 hours 1 hour 30 minutes
AB-312 24-36 hours 1 1/2 hours 1 hour
B-31 2 hours 1 hour