Making Latex Molds and Casts

Latex rubber is a popular choice for making both molds and casts. Latex has several useful properties and it is also relatively easy to make both latex molds and casts by following the right procedures.

Liquid latex rubber is a versatiles material that is considered tough, durable and economical as well. It lends itself well for various applications in the fields of mold making and casting.

Latex molds capture details well and are usually used to make plaster and resin casts. They are also handy for casting abrasive materials like concrete as the mold will not tear despite the coarseness. The latex can also be applied on architectural details on the walls or even ceilings without the latex running off. This works especially well for making molds for restoration works.

Latex casting is usually used for making hollow molded rubber articles, toys, balls, imitation pottery, display items and flexible props. Liquid latex is popularly used for mask making as well as special effects works like wrinkles, scars and gashes for theatre, television and films. It is even commonly used as an adhesive for bald caps.

Apart from this, latex is useful for slushing casting clays for ceramic works and for coating polystyrene and other fabrics and even tools. This forms a protective and water proof coating on the items. It even allows for better handling and insulation for the tools.

How to do?

It is easy to use latex rubber for making molds and casts. The most common method is dipping for mold making and pouring for casting - No elaborate process or expensive molds are required.

Latex molds are created by dipping the model directly into the latex rubber itself. Simply dip the model into the container to get a uniform coating and then let it dry. Repeat the procedure 10 to 12 times to build up the adequate thickness. Alternatively, the latex can also be painted on the model multiple times, while allowing each subsequent coat to dry properly.

The procedure for making latex casts is also quite similar. Here, the latex rubber is poured into the mold and allowed to sit for some time. Then the rubber is poured out again. A thin film gets deposited on the inner side of the mold and will dry to form a flexible cast. Keeping the latex inside for a longer time or repeating the procedure will increase the thickness of the latex cast.

Usually plaster molds are preferred for making latex castings. This is because the porous plaster will absorb the water in the latex and allow it to cure to form a cast. Therefore, latex and other molds are generally not preferred for latex casts.

Demolding liquid latex molds and casts is also simple as they can be easily peeled off the model or mold. However, it is advisable to dust the latex surface with talcum powder before demolding, else the latex will stick to itself. Latex casts can be painted with special latex paints to get the desired finish.

Sodium Silicate Deflocculates Clay Slips

Slip casting is a common technique used for the mass production of complicated ceramic items. It is made by mixing dry clay with water along with an effective deflocculant like sodium silicate.

Pottery is the common method used to make pots, dishes and other items using clay or other ceramic materials. The potter fashions the piece on the wheel with his hands and it is then fired to give it a hard and durable form. However, there is another technique for making hollow ceramic and porcelain articles in complex shapes that cannot be fashioned on a potter’s wheel. This is known as slip casting of clay, usually along with sodium silicate.

Slip casting is a simple technique of pouring thinned clay into a mold. The mold is filled to the brim and the clay is allowed to settle inside. This allows the slip to build a thin layer inside the mold after which the excess material is drained out. The amount of time the clay slip stays inside the mold will dictate the thickness of the cast.

The clay is allowed to cure and demolded once it starts to separate from the sides of the mold. Usually, slip casting is done in plaster molds as the porous plaster will absorb the water from the slip and allow for quick casting.

When it comes to making the slip for casting, people usually assume that it is done by mixing clay with water. However, this requires a lot of water which in turn will take a long time to shrink and dry. Moreover, the clay may not disperse properly in the slip and will settle at the bottom of the mixture. This is why a deflocculant like water glass (chemical name – sodium silicate) is mixed with the clay before adding water. This will thin the clay or reduce its viscosity by dispersing its particles and thus require much less water. But it should be kept in mind that excess sodium silicate will have an opposite effect and will actually make the clay thicker or flocculate it!

Top quality liquid sodium silicate can be sourced from EnvironMolds at