Archaeological artifacts have special significance when they can be held, touched and studied.  Originals are locked safely away in museums, but duplicates can be made with similar experiential results.  The process of making reproductions requires molds to be made.   A 2 part epoxy fills the molds making a cast artifact.  This activity is within reach of high school students.
Archaeological artifacts have special significance when they can be held, touched and studied.  Originals are locked safely away in museums, but duplicates can be made with similar experiential results.  The process of making reproductions requires molds to be made.   A 2 part epoxy fills the molds making a cast artifact.  This activity is within reach of high school students.

© 2008, Najuqsivik Community Museum. All Rights Reserved.

Example of Dorset face in silicone mold

Original archaeological artifacts are locked away in secure museums, available only through pictures. But, some artifacts can as obtained as reproductions, which in turn can be reproduced after molds are made. Thus significant artifacts can be studied up close.

John Jamieson
Aibilee Amitook

© 2008 Najuqsivik Community Museum. All Rights Reserved.


RTV3110 Dow Corning Silicone

RTV3110 is the material of choice to make exact reproductions in molds. It requires a catalyst and takes approximately 24 hours to set up. The cost is approximately $300 per gallon and it makes many molds.

John Jamieson
Aibilee Amitook.

© 2008 Najuqsivik Community Museum. All Rights Reserved.


Wax can be heated on a hot plate

Paraffin wax will be used as the substrate to hold the artifact. It can be recycled and easily cleaned up.

John Jamieson
Aibilee Amitook.

© 2008 Najuqsivik Community Museum. All Rights Reserved.


Establish a base of wax and add artifact

After a base of wax is established, approximately 1/2 inch thick, the artifact is placed and wax is added to surround the artifact about half way up the side. The mold will consists of 2 halves. Thus there will be a parting line where the two molds meet. Carefully select where you want the wax to extend on the artifact, since it will establish the location of the parting line, which will be called the 'flashing'.

John Jamieson
Aibilee Amitook

© 2008 Najuqsivik Community Museum. All Rights Reserved.


Trim the wax platform

Trim the wax leaving about 3/4 inch to 1 inch around the outside of the artifact.

John Jamieson
Aibilee Amitook

© 2008 Najuqsivik Community Museum. All Rights Reserved.


Locking and overflow channels

Two channels must be carved into the wax. The first channel, about 1/8" wide and 1/8" deep will be about 1/4" from the artifact. This channel will act as the overflow for the epoxy which will be added later. The second channel on the outside of the overflow channel is the same size, but it will be used as a locking channel to allow the 2 halves to exactly fit together at the correct location.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Build a dam around the wax.

It is necessary to contain the liquid silicone and this is accomplished by a plastic dam around the wax. Use liquid paraffin to seal the bottom of the dam. Use masking tape to secure the end of the plastic dam. If any leaks are found after adding the silicone, liquid wax can be quickly added to plug it.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Silicone and catalyst mix 10:1

Wear rubber gloves. Mix coloured catalyst fully into the silicone. It sets up overnight. Silicone sticks to itself, so have vaseline handy when pouring the second half of the mold, to act as a mold release.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Mixing catalyst into silicone

Use a plastic container to hold the silicone. Add the catalyst in 10:1. For faster curing add more catalyst. Some catalysts 'kick' fast, but S for slow catalyst works fine. Mix thoroughly to a uniform colour.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


A vacuum assures no air bubbles on artifact.

A vacuum will draw out air entrapped during mixing. The process can work without a vacuum pump, but you must be careful to make sure bubbles do not accumulate on the artifact. Small amounts of air are not a major problem for most artifacts.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Slowly pour silicone over artifact

Start at one end of the wax and slowly pour the silicone. Let the silicone roll forward on its own. This allows air to be pushed away from artifact. Once the artifact is covered you can quickly spoon the silicone over the surface. Set it aside overnight, or longer if you like.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Remove wax to prepare for next pouring

If the silicone has cured and is hard, flip it over gently and pry off the wax. Be careful and do NOT allow the artifact to move out of the wax, OR ELSE YOU MUST START THE ENTIRE OPERATION AGAIN! Gently remove the wax, exposing half of the artifact and the silicone.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Apply a thin layer of liquid vaseline on the silicone mold.

Before pouring the other half of the mold, warm some vaseline and coat the silicone with a thin layer. Do not apply the vaseline to the artifact. Vaseline prevents the silicone from sticking to itself. The silicone is applied as before and allowed to cure overnight. Open the mold and remove the artifact the next day.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Add Electrical Resin #5 to a plastic container

Scotchcast Electrical Resin #5 comes in Part A and B. They are mixed in a ratio of 2:1. Add Part A to a plastic container. Use plastic gloves. Part A is very thick. Record the tare weight of the container.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


epoxy, Electrical Resin

Part B is very liquid and should be added to Part A in a fume hood. There are ammonia fumes that are released. One part of B to 2 parts of A. Fumes are eliminated after stirring the solutions together.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Fumed silica thickens the epoxy

After mixing Part A and B, it is necessary to thicken the mixture to prevent running when added to the mold. Add fumed silica powder. To simulate old ivory, some white oil paint and Naples Yellow oil paint are added to the mix. Other colours can be added now, or added when the artifact has hardened. Use a fume hood.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


epoxy, mold,

Once the epoxy has been mixed it is added to the 2 halves of the molds. Use a stick to push the epoxy. Try to avoid trapping air. Don't fill too much, since it will be pushed out of the artifact area and form a thick flashing around the artifact.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Align the 2 halves and press together

The mold has 2 channels. A groove must be cut in the protruding groove to create a 'V'. This will allow excess epoxy that is squeezed out of the mold to go into the space and become part of the flashing. Apply pressure to the mold after it is put together. Usually several books are sufficient.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Open mold gently

After sitting overnight, gently pry the 2 halves apart and twist the mold to release the artifact. Remove overflow from the channels. When the mold becomes very old, it is useful to spray in some mold release to keep the silicone from becoming too dry and sticking to the artifact. Professionals use the mold only about 10 times before replacing. You can expect about 40-60 reproductions before replacing when used for small museums.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Cut away flashing

A thin layer of hardened epoxy will be formed at the meeting of the two molds. Cut it away before painting.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Oil paints for artifact

Oil paints and paint thinner are used to colour artifacts. Burnt Umber is the main colour to simulate old ivory. Apply the oil and briefly wait before rubbing off. Paint thinner can remove the colour if incorrect. After drying, a spray lacquer can be used to seal in the colour. A Borden number specifying an archaeological artifact should be added if required.

John Jamieson
Aibilee Amitook

© 2008, Najuqsivik Community Museum. All Rights Reserved.


Learning Objectives

Mold making is a skill used in many trades, from dentistry, the automotive industry to archaeological reproductions. Two main methods are vulcanization with rubber using heat and pressure and the second is done at room temperature using silicone. This activity will use silicone and epoxy to make the artifact.

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