![]() It may be necessary to first mold the piece, then pour a casting out of Smooth Cast resin to use as an original, as Smooth Cast resins are somewhat solvent resistant. The original must be made of a solvent-resistant material, or coated with a solvent resistant spray. The mold rubber should be vacuumed or pressure-molded to reduce air bubbles when using this method. To reduce a piece, make a mold of your original using Mold Max 30 with Fast Cat 30 as catalyst or Body Double silicone with NOVOCS solvent mixed into the catalyzed silicone mold rubber. Reducing a piece is somewhat more difficult than enlarging a piece. ![]() The following chart may assist in determining the expansion rates you may experience: Please note, an expanded mold will be more fragile and may require extra care in handling. A light mist coating of Ease Release™ 200, while optional, may help to allow for an easier demold.įurther expansion can be achieved by repeating this process. Once the surface is dried, a batch of Smooth Cast 300Q or duoMatrix NEO can be mixed and poured into the mold. The solvent will begin evaporating immediately, so you must work quickly. Once the mold has expanded, the mold should be removed from the solvent bath, and the surface should be thoroughly dried. Make sure the solvent bath completely covers the mold or distortion may occur. A mold soaked in toluene for 7 days expands approximately to 130% of the original size. ![]() Over time, an expansion of up to 200% can be reached. The solvent will become absorbed into the silicone rubber, enlarging the mold. Observe all safety precautions when handling combustible or flammable solvents. Toluene, xylene or naptha are also suitable. The mold is then soaked in a sealed container in a bath of solvent. The mold rubber should be vacuumed or pressure-molded if possible to reduce air bubbles. The mold is enlarged instead of enlarging a casting because a solvent filled silicone casting is quite difficult to handle and nearly impossible to make a second mold of. To enlarge a piece, a mold of the original is made using Mold Max 30 with Fast Cat 30 or Body Double. Smooth-Cast™ 300Q is recommended for a casting resin, as the speed of the cure does not allow the solvent to affect the surface of the casting. Body Double has a high level of curatives, which allow it to perform well in a solvent-heavy application. Mold Max 30 with Fast Cat accepts solvent readily, coming to a full cure even with a large amount of solvent added. To enlarge or reduce a piece, it is recommended that Mold Max™ 30 with Fast Cat™ 30 as catalyst or Body Double™ be used as a mold material. Here are examples using two different mold making rubbers for these purposes. Once the rubber mold has expanded or shrank, you can cast a Smooth-On plastic into the mold. You can accomplish this by either shrinking or expanding a rubber mold using solvent.
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