How To Cast Smooth‑Cast™ 325 Urethane Resin


In this resin casting tutorial video, we demonstrate how to mix and pour Smooth Cast 325 liquid plastic resin.

The original 2-piece mold is made with Mold Star 15. Begin by closing the mold.

Smooth-Cast 325 Colormatch Resin
1:1 Mix Ratio, Low Viscosity, Fast-Curing, and Clear Amber Color

Dispense equal parts 1A:1B by volume. Cast Magic Gold Rush effects powder can be added to create a unique look. Add Cast Magic Gold Rush to Part B. Mix Cast Magic into Part B thoroughly. Combine Part A with Part B and mix thoroughly. Slowly pour the mixed resin into the mold. Place plastic board over the pour spout. Carefully life mold. Keep mold halves pressed firmly together. Slowly roll resin inside the mold for 15 seconds. Purpose: Helps minimize surface bubbles in casting. Remove the plastic board. Allow Smooth-Cast 325 to cure. Casting is demolded after 20 minutes.

Carefully trim pour spout. Sand pour spout area smooth. Casting is ready for painting. Optional: Paint casting with acrylics. Create amazing effects by combining different Cast Magic powders with Smooth-On colorants.

Smooth-Cast® 325 ColorMatch® plastics are fast-cast resins that were developed specifically for adding color pigments and fillers to achieve true color representation or filler effect. The ColorMatch® Series is formulated "color neutral". 

Small amounts of pigment will yield accurate, vivid colors from cured castings (use of Smooth-On SO-Strong® pigments is highly recommended). Because of its neutral color, the ColorMatch® Series is ideal for creating marble and wood grain casting effects, or duplicating the look of real metal by adding bronze, brass or other metal powder.