Silicone Block Mould – Pt.1

1-Piece Silicone Block Mould (Part 1)
By Paul Carnall
A M T Composites

This is a 2 part Project. In Part 1 we made a 1-piece Silicone Block Mould of the “Artichoke Tea Light Candle Holder” using a 2 part room temperature cure silicone moulding rubber.
Then, in Part 2, we cast into the silicone mould using “Metal Cold Casting Technique” with Bronze powder
Part 1: Making a 1-piece Silicone Block Mould

Requirements for Mould

  • Original Artichoke Tea Light Candle Holder made from glazed porcelain (or other original)
  • Ease Release 200 (releasing agent)
  • 500ml Plastic container (large enough to fit original model into)
  • Glue gun
  • Mold Star 15 silicone part A & part B
  • 2 x mixing containers (non-pourous)
  • Wooden spatula for mixing silicone
  • Instructions for Mould making

Step 1: model preparation.

  1. In order to make a “Silicone Mould” (the negative shape), one needs to have an original model to replicate (the positive shape). Our original model was an Artichoke Tea Light Candle Holder made from glazed porcelain, so surface porosity was not a concern.
  2. If you use a different original model made from a porous material like wood or concrete, a sealing agent must be applied to seal up surface porosity. Superseal is ideal for this application.
  3. Next is to apply the Ease Release 200 release agent so that the silicone, once cured, can be demoulded from the model without sticking.

Step 2: retaining walls

  1. Moulding silicone, before it cures, is a liquid material. We used a 500ml plastic bucket that the original model fitted into nicely to contain the liquid moulding silicone. “Waterproof” retaining walls can be made from melamine, plastic, modelling clay, etc.

Step 3: secure the model

  1. Secure the original model to the bottom of the plastic bucket using a heat glue gun so that it doesn’t move while pouring the liquid silicone.

Step 4: mixing and pouring the liquid silicone

  1. Blend Mold Star 15 silicone part A & part B together thoroughly by stirring deliberately and scraping the sides and bottom of the mixing container. Ideally, mix in one container then transfer into a new container and repeat the process. Do not whip material as this will introduce undesired air into the mix.
  2. Once silicone is correctly mixed, pour carefully into the plastic bucket, covering the entire model. Pouring from a height of approximately 30cm in a thin stream will reduce air bubble entrapment in the silicone.
  3. Also remember to work on a level surface so that your mould is straight.

Step 5: allow to cure and demould

  1. The Mold Star 15 silicone has a cure time of 4 – 6 hours at room temperature (23 C).
  2. Once the relevant cure time has passed, carefully and slowly demould:- take the mould out of the plastic bucket and then remove the original model from the cured silicone mould.
  3. Congratulations! You now have a silicone mould that can be used to produce many replicas of the original model.
  4. See the instruction sheet for Part 2 to learn how to cast into the silicone mould you’ve just made, using “Metal Cold Casting Technique” with Bronze powder.