Sealer and Release Agent Reference Guide

Sealer and Release Agent Reference Guide

For sealing and releasing your model, you can use the below charts as a general guide for making molds using urethane rubber or silicone rubber. The best way to determine the appropriate sealer and release agent for your application is to read the product technical bulletin.


When You Are Making a Polyurethane Rubber Mold . . .

and your original model
is made of...
seal it with... then apply...
Modeling Clay - Water Based Spray Shellac* Universal® Mold Release
Modeling Clay - Sulfur Based Spray Shellac* Universal® Mold Release
Modeling Clay - Sulfur Free Spray Shellac* Universal® Mold Release
Wax Spray Shellac* Universal® Mold Release
Foam (Polyurethane) Spray Shellac* Universal® Mold Release
Non Porous Hard Plastic Not Required Universal® Mold Release
Wood Super Seal®,
Sonite® Wax**,
or Spray Shellac*
Universal® Mold Release
Plaster / Gypsum Super Seal®,
Sonite® Wax**,
or Spray Shellac*
Universal® Mold Release
Stone / Concrete / Cement Sonite® Wax** Universal® Mold Release

General Information

  1. The above combinations of sealers and release agents are necessary for successfully making rubber molds using Smooth-On PMC®, ReoFlex®, VytaFlex® and Brush-On® rubber mold compounds.
  2. Porous materials need to be sealed, followed by a release agent before applying mold rubber.
  3. Nonporous materials require only a release agent before applying the mold rubber.
  4. *Don’t use Acrylic Spray! - Universal® Mold Release can soften the acrylic making the rubber bond to the model.
  5. **Sonite® Wax is suitable for sealing a variety of surfaces. It is available from Smooth-On and its distributors, Butcher’s Wax can be substituted in a pinch.

When You Are Making a Silicone Rubber Mold...

and your original model is made of... seal it with... then apply...
Modeling Clay - Water Based Acrylic Spray** (optional) Ease Release® 200 (optional)
Modeling Clay - Sulfur Based* Acrylic Spray** (optional) Ease Release® 200 (optional)
Modeling Clay - Sulfur Free Not Required Ease Release® 200 (optional)
Wax Not Required Not Required
Foam (Polyurethane) Acrylic Spray** Ease Release® 200 (optional)
Non Porous Hard Plastic Not Required Not Required
Wood Super Seal®,
Petroleum Jelly,
or Acrylic Spray**
Ease Release® 200 (optional)
Plaster / Gypsum Super Seal®,
Petroleum Jelly,
or Acrylic Spray**
Ease Release® 200 (optional)
Stone / Concrete / Cement Super Seal®,
Petroleum Jelly,
or Acrylic Spray**
Ease Release® 200 (optional)

General Information

  1. Your best bet is to refer to the specific product technical bulletin for the mold rubber that you are using.
  2. The above combinations of sealers and release agents are suggested for successfully making rubber molds using Smooth-On Mold Max®, Smooth-Sil®, Dragon Skin®, EcoFlex®, OOMOO® and other silicone mold rubbers.
  3. Use only sealers or release agents that are compatible with silicone rubber such as Ease Release® 200, proven and reliable. Apply a light mist coating, brush release over surface detail, apply second light mist coating and let dry.
  4. *Modeling Clay - Sulfur Based cannot be used with Platinum Silicone under any circumstance.
  5. **Don’t Use Shellac! – shellac contains alcohol and the rubber will bond to the model.
  6. Don’t wipe model down with alcohol prior to applying silicone rubber.

Click here to download a pdf of the Sealers and Releases charts.