Mold builder - liquid latex rubber for making your own molds large and small. A smooth-flowing liquid latex that you can brush over models to create flexible molds that will produce many plaster castings. Just brush on several thin air-drying coats of Mold Builder and peel off a ready to use rubber mold. Mold Builder reproduces fine details, has good elongation and stretch. High solid content produces quick build-up. Simple water clean-up. General instructions for making molds and shells is furnished with each can. For complete instructions see our book “How to Make Latex Molds.

Mold Builder latex rubber is a one-component system that requires no mixing, it is ready to use right out of the container.  Our latex rubber is relatively inexpensive, compared to other mold making products. It is an elastic mold rubber and molds are generally thin-walled, strong and exhibit good abrasion resistance. Because of its high elasticity, a feature unique to latex rubber, it has the  ability to be removed from a model like a glove. A latex mold will retain its shape after being repeatedly rolled up and away (and turned inside out) from an original model or casting – like a glove. Because of this feature and its resistance to abrasion, latex is commonly used for making “glove molds” in the reproduction of ornamental concrete (lawn ornaments and statuary). Latex molds are also good for casting wax and gypsum. 

Although our Mold Builder, liquid latex rubber, is harmless to most surfaces, always test an inconspicuous area first prior to applying over the entire surface. Next, some models have holes or “tunnels” that extend completely through the piece. Here, the hole under the puppy’s stomach, has been completely filled with children’s modeling clay. Clay has also been formed around the edge of the base, filling the gap between model and base.

To apply, simply brush the liquid over the surface of the model, then around the base to create a flange. Allow the Mold Builder to air dry or use a hair drier on a warm setting to speed up the drying. Important: the first two coats must be applied as thin as possible. Remove all thick pockets which if left will seal over and not dry out. Once the surface has dried (translucent appearance) you can apply another coat. Allow the combined layers to gradually achieve proper thickness. Example: A 6” life-like figurine requires approximately ten coats. For added firmness and support, apply a layer of cheese cloth or bandage gauze between your last layers.

When your mold is dry, dust it lightly with talc powder, then peel it off of the model. Dust the inside of the mold with talc powder to keep the fresh latex from sticking to itself. Support the mold in a cardboard box (as shown) and pour in the liquid casting material of your choice.

You can make the flat (“blanket” mold as pictured) just as easily as the “glove” type. The model (usually a “plaque-like” piece or wall sculpture) is attached to a base, using small dabs of plasticene clay. Again, use plasticene clay to fill the gap around the edge, giving a good, clean edge to the resulting mold.

Apply enough Mold Builder to give a thick “blanket” of latex (as shown in this cross section). The latex is allowed to dry ‘and is trimmed flush with the base.

Retaining sides are added to contain plaster. These sides can be of any rigid material that will hold the plaster as it sets. With a brush apply a light solution of liquid soap and water over the latex “blanket” mold and allow to dry. This soap solution when dry will act as a mold release allowing the pieces to be separated later. Next pour plaster over the rubber blanket to form a supportive base for the flexible latex Mold Builder. Mother support mold option is to pour sand or kitty litter into a shallow box. Leaving the original piece in your mold, press the mold into the sand or kitty litter to create an impression. Once the impression is made, carefully remove your mold. Pull original from mold, then place mold back into sand or kitty litter.

When the plaster “support” mold has set up, the sides are removed. The plaster is lifted off, and then the latex mold is peeled from the model. Replace the latex mold into the “support” mold, and pour in the casting material of your choice.

1. Use only dry warm air for drying and curing Mold Builder.
2. Do not use petroleum based mold release agents. Petroleum release agents will react with the latex mold and destroy it.
3. Clean up Mold Builder with cold soapy water only. Do not use warm water which will cause the Mold Builder to set up immediately!
4. A few minutes prior to using Mold Builder, remove the lid and allow the accumulated ammonia to dissipate.
5. To remove from clothing, clean with dry cleaning solution.