Tooling & Mould Making Supplies

Frequently Asked Questions

• What tooling supplies are needed to make a rubber mould for concrete castings?

  The tooling supplies you need depend on the stage of the mould-making process you are at, but a well-stocked bench for GFRC and concrete mould work typically includes:

  • Smooth-On Sonite Wax — a paste wax used to prepare and condition non-porous mould surfaces such as fibreglass and cured urethane. Typically applied before a chemical release agent to improve release performance and protect the mould surface over multiple uses
  • Sculptex Modeling Clay — used for sealing mould joints, creating chamfers and cove profiles in corners, and building up detail elements within a form before casting
  • Stainless Steel Caulking Tools — for pressing and smoothing clay into corners and joints cleanly and precisely
  • Smooth-On Turbine Mixer — a drill-mounted mixing paddle designed for mixing silicone and urethane rubber compounds before pouring
  • Smooth-On Mixing Containers and Mixing Sticks — for accurately measuring and mixing two-part mould-making compounds at the correct ratio

  For guidance on mould preparation and casting techniques, visit the Knowledge Hub or join a GFRC training course.

• How do I prepare a master before making a silicone or urethane mould?

  Your master is the original shape you take the rubber mould from, so its surface finish carries straight into every concrete cast. How you prepare it depends on what it’s made from.

  Porous masters such as foam, MDF, timber, plaster and raw clay can absorb liquid rubber, leave bubbles in the mould surface and make demoulding difficult. Seal these first with Smooth-On Super Seal, then apply a release agent before pouring your silicone or urethane.

  Non-porous masters such as fibreglass, cured urethane or melamine usually need only Ease Release 200 and in some cases, Sonite Wax. A clean, smooth, correctly sealed master gives you a mould that captures fine detail and lasts for many casts. Visit the mould forms and prep products page for the full range of release agents and prep supplies.

• When should I use a release agent in mould making?

  Release agents stop your rubber from bonding to the master, so they go on after sealing and before you pour. Which one to use depends on your master and the rubber you’re using.

  • Sonite Wax: A paste wax that gives sealed porous and non-porous masters a smooth barrier layer. Apply a thin coat, buff it and repeat if needed before pouring.
  • Ease 200: A spray-on release agent*. A fast option for masters with detail, undercuts or large surfaces that are tricky to wax by hand.

  Always test on a small area first. Some rubbers and master materials react with certain release agents.