Tutorial: How to Make a Silicone Rubber Candle Mold

The following tutorial details the process of making a silicone rubber mold for casting wax to make candles.

 

Supplies Needed for Project:

 
 

Step 1: Select a Model

Select or create a model to replicate. The final wax candle will be a copy of this original model. Many candle makers sculpt their original models with clay, wood or wax or utilize computer-based options like 3-D printers and CNC routers to produce their designs.

The model that we selected for this particular project is made of glass:

 

Glass Object for Making Mold

 

This glass model is hollow; however, we would like the final candle to be solid, so we fill the model with wood and clay:

 

Inserting Wood

Wood Inserts

Fill Model with Clay

 

The mold rubber will pick up every detail of the model, so the clay is carefully smoothed out:

 

Even out Clay

 

Smooth Clay in Model

 

 

Step 2: Construct a Mold Box & Secure the Model

To make a one-piece poured block mold, construct a mold box or select a suitable container to place your model in. Make sure that there is enough space between the model and the mold box walls to create mold walls with an appropriate thickness.

We leave approximately 1″ of space for mold walls and the mold bottom in this example.

Plywood is being used to construct the mold box. Porous materials like this must be sealed prior to pouring liquid mold rubber. The plywood will be sealed in Step 3.

Some other possible options for mold boxes or mold containers: Plexiglas®, plastic pails, PVC pipe, Sonotubes®, melamine-laminated particle board (you can purchase a 24″ H mold box directly from Polytek).

 

Cutting Plywood for Mold Box Walls

 

Using a hole saw, we create a hole in the bottom board of the mold box to hide this part of the model (we do not want this protrusion on the final candle):

 

Protrusion in Glass

Cutout

Cutting Hole in Wood

Hole in Plywood

 

Securely adhere the model to the bottom board so it does not float when the mold rubber is poured around it.

Using PolyPoxy®  Quick Stick Adhesive, a two-part, fast-setting epoxy adhesive, we adhere the model to the bottom board:

 

Epoxy Adhesive for Mold Making

 

PolyPoxy® Quick Stick Adhesive has a 1:1 mix ratio and sets in 3-5 minutes.

 

Apply Epoxy Adhesive

Adhere Model in Bottom Board with Epoxy

Model on Baseboard (2)

 

While the epoxy is curing, construct the walls of the mold box:

 

Construct Mold Box

Construct Plywood Mold Box

Finished Mold Box

 

Step 3: Apply Sealer & Release Agents as Necessary & Finish Preparing the Model

Apply appropriate sealers and/or release agents to the mold box.

As mentioned previously, the plywood used for this mold box is not sealed. We coat it with Pol-Ease® 2350, a white petrolatum dissolved in mineral spirits, which serves as both a sealer and release agent. No additional release agent is necessary.

When using a non-porous mold box, consider applying Pol-Ease® 2500 Release Agent instead (Use this option when working with silicone rubber. Use Pol-Ease 2300 Release Agent when working with polyurethane rubbers).

Not sure which release agent to use for your particular project? Our Sealer & Release Agent Selection Guide may be helpful.

 

Pol-Ease 2350 Sealer and Release Agent

Apply Sealer to Mold Box

 

Apply a release agent to the model.

We also apply Pol-Ease 2350 Sealer & Release Agent to the model itself. Pol-Ease® 2500 Release Agent (an aerosol spray) is another option that could be used in this case (for use with silicone mold rubbers).

 

Polytek Sealer and Release Agent

 

Allow sufficient time for the solvent in Pol-Ease 2350 to evaporate (~1 hour, depending on temperature and humidity) before moving on to the next steps.

Seal any areas around the model where rubber may leak. There are small gaps at the base of this model, so we seal that area with plasticine clay (warmed up for easier application). Other options for sealing include caulk and hot glue.

 

Clay Snakes

 

Smooth and flatten the clay as best as possible:

 

Smooth Clay

Clay Caulking

 

Place the model in the mold box and secure the bottom board to the mold box walls:

 

Assemble Mold Box

Secure Mold Box

 

Place the mold box and model in the proper position for pouring the liquid rubber:

 

DSC06980 - Copy

 

Seal the edges of the mold box with plasticine clay to help prevent rubber from leaking outside of the box:

 

Clay Snakes - Caulk Box

Mold Box Sealed with Clay

 

Step 4: Measure, Mix & Pour Silicone Rubber

The mold rubber selected for this particular project is PlatSil® 73-15 Silicone Rubber.

Basic Specifications for this Rubber:

  • Type of Silicone: Platinum-Cured
  • Mix Ratio: 1A:1B
  • Shore Hardness: A15
  • Pour Time: 20 minutes
  • Demold Time: 4-5 hours
  • Color: White Translucent
  • Mixed Viscosity: 2,500 CP

 

NOTE ABOUT CURE INHIBITION: Contamination from amines, sulfur, tin compounds, polyester resins, some 3D-printed plastics, and some other materials can cause cure inhibition in platinum-cured silicone rubbers, so ensure that your model and other materials coming into contact with the silicone do not contain these inhibitors. It is best to perform a small test cure on your model before pouring a large mold.

This particular mold requires approximately 10 lb of PlatSil 73-15 rubber (5 lb of Part A & 5 lb of Part B).

 

PlatSil 73-15 Silicone Rubber for Candle Making - Polytek


 
Weigh out Part B on a digital scale – we recommend pouring Part B first because it is lower in viscosity than Part A and is less likely to cling to the sides of the mixing container:
 

 

Part A of PlatSil 73-15 Silicone Rubber


 
Tare the scale and weigh out Part A into the same mixing container.

 

Part B of PlatSil 73-15 Silicone Rubber


 
Thoroughly mix Part A and Part B together, scraping the sides and bottom of the mixing container several times:

 

Mix Silicone Rubber Thoroughly


 
Carefully pour the mixed rubber into the mold box. Pour into one corner and allow the rubber to rise. Do not pour rubber directly onto the model:

 

Pour Silicone Rubber into Mold Box

 

 

Soft Silicone Rubber

 

 

Allow Silicone Rubber to Cure


 
PlatSil 73-15 can be demolded in 4 to 5 hours at room temperature. If a different rubber is being used, make sure to check the demold time of that particular rubber. Demolding too soon can cause permanent warping of the mold.

 

Step 5: Demold & Cut Mold (if necessary)

Carefully remove the mold box bottom board and walls. A putty knife may be helpful in this process:
 

Remove Mold Box

 

Remove Mold Box Bottom Board

 

 

Carefully Remove Mold Box

 

 

Remove Wood and Clay


 
Depending on the shape of the model, the mold may have to be cut to remove the model and subsequent castings. We use a scalpel to cut an irregular pattern on one side of the mold (irregular patterns realign better for casting than straight cuts):

 

How to make a cut in Silicone Mold

 

 

Make Irregular Cut in Mold


 
Carefully remove the model from the mold:

 

Polytek Silicone Mold

 

Finished PlatSil 73-15 Silicone Candle Mold


 
Make a small hole in the bottom of the mold to later accommodate a wick:

 

Make Hole in Rubber Mold for Wick


 
This next step is completely optional. Before we move on to casting wax, we make a plastic copy of the original model just in case we need to make more molds at a later date (we broke the original glass model when demolding).
 
Wooden boards and duct tape are used to support the mold when casting (you could also use the original mold box for support):

 

Prepare Mold for Casting Plastic


 
EasyFlo 60, a fast-setting polyurethane plastic, is poured into the mold to make the copy:

 

Casting EasyFlo 60 Liquid Plastic


 
This plastic can be demolded in 15-30 minutes:

 

Plastic Copy of Candle

 

 

EasyFlo 60 Decorative Element

 

Step 6: Pour Wax into Mold

Feed a wick through the hole created earlier:

 

Place Wick in Silicone Mold

 

Candle Making with Silicone Mold


 
Temporarily tie a knot in the wick:

 

Knot in Wick

 

 

Wick in Silicone Mold


 
Secure the wick above the pour hole of the mold. Make sure it is centered:

 

Suspend Wick for Wax Casting

 

 

Secure Wick with Clip


 
Melt wax with the appropriate equipment and add dyes and fragrances if desired:

 

Wax in Parrafin Bath

 

 

DSC07282


 
Carefully pour the wax into the mold:

 

Casting Wax in Polytek Silicone Mold

 

 

Allow Wax to Cool in Silicone Mold


 
Allow the wax to completely cool:

 

Demold with Wax is Cooled

 

Step 7: Remove Candle from Mold

Carefully remove the candle from the mold:
 

Remove Candle from Mold

 

DSC07399


 
Trim the wick as necessary:

 

Trim Wick on Both Ends


 
Hundreds of candles can be made in this single mold. A finished candle is pictured below:

 

Decorative Candle from Silicone Mold

 

 

Close-Up of Candle Detail from Mold

 

 

Candle Making Tutorial

 

 

We utilized a soft, silicone rubber for this tutorial; however, polyurethane rubbers are also a viable option for candle making. Some waxes perform better in silicone molds vs. polyurethane molds. Please get in touch with us to discuss your specific candle-making project:

Call us at 800.858.5990.
Email us at sales@polytek.com.
Fill out this simple online form.