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silicone mold materials

Dow Corning Silicone Rubber

Silastic 3110 RTV Silicone Rubber is Dow Corning’s lowest viscosity two-part silicone rubber. It has a viscosity of 14,000 cps with a Shore A hardness of 45 and a tear strength of 15. It easily fills tiny crevices and indentations and is very easy to work with and pour. It offers a wide choice of handling and curing physical properties. No vacuum deairing is required. It is ideal for capturing intricate details in art objects and simple shapes. There is no inhibition sensitivity to modeling clays and most adhesives, which could cause incomplete cure of mold. It does have moderate dimensional shrinkage. Curing times can be varied depending on the catalyst type and amount of catalyst used.

Silastic E RTV Silicone Rubber is one of Dow Corning’s highest viscosity two-part silicone rubber. It has a viscosity of 100,000 cps with a Shore A hardness of 35 and a tear strength of 100. It has a long working time and is heat-accelerable curing. It has high elongation and virtually no shrinkage. It is especially good for patterns with unusual configurations, severe undercuts and close tolerances. Vacuum deairing is required. There is inhibition sensitivity to some modeling clays and adhesives which could cause incomplete cure of mold.

Silastic HS II RTV Silicone Rubber is one of Dow Corning’s low viscosity two-part silicone rubber. It has a viscosity of 45,000 cps with a Shore A hardness of 20 and a tear strength of 120. The main difference in this Silastic from the others is its high strength and long mold life, which allows more reproductions per mold. It easily fills tiny crevices and indentations and is very easy to work with and pour. It offers a wide choice of handling and cured physical properties. Vacuum deairing is required. It is especially good for patterns with unusual configurations, severe undercuts and close tolerances. There is no inhibition sensitivity to modeling clays and most adhesives which could cause incomplete cure of mold. It does have moderate dimensional shrinkage.

Silicone Cat Ratio R/C Working Cure Tear Viscosity cps

Type Type By Weight Time Time Strength Hardness Shore A

5:1 1 hr 18 hrs 15 14,000 / 45

1 10:1 2-1/2 hrs 24 hrs

20:1 4 hrs 48 hrs

Do not use less than 10% of #F Catalyst

3110 F 10:1 2 min 2 hrs

20:1 13 min 4-1/2 hrs

100:1 4 min 20 min

4 200:1 10 min 1-1/2 hrs

400:1 60 min 2-1/2 hrs

E E 10:1 2 hrs 24 hrs 100 100,000 / 35

100:1 4 min 20 min 120 45,000 / 20

HS HS 200:1 10 min 1-1/2 hrs

400:1 60 min 2-1/2 hrs

Cat. No. Description Price

CA-10105-001 Silastic 3110 / Cat 1, 1 lb. Kit $ 37.98

CA-10105-010 Silastic 3110 / Cat 1, 10 lb. Kit 309.00

CA-10107 Catalyst #1, 0.1 lb 3.98

CA-10110-001 Silastic 3110 / Cat 4, 1 lb. Kit 37.98

CA-10110-010 Silastic 3110 / Cat 4, 10 lb. Kit 309.00

CA-10112 Catalyst #4, 4.5 Gram 3.98

CA-10115-001 Silastic 3110 / Cat F, 1 lb. Kit 37.98

CA-10117 Catalyst #F, 4.5 Gram 3.98

CA-10125-001 Silastic E / Cat E, 1 lb. Kit 42.57

CA-10135-001 Silastic HS II / Cat HS, 1 lb. Kit 37.98

Smooth-On Silicone Rubber

Smooth-Sil 900 is an alternative to Silastic 3110. This material is a two component silicone rubber compound that features a convenient one-to-one by volume mix ratio (no scale necessary). It has a relatively low viscosity for easy mixing and pouring. Because of its low viscosity, vacuum deairing is not necessary. This material cures at room temperature with negligible shrinkage. It is suitable for making molds for sculptures, reproductions, casting plaster, resins and wax.

Smooth-Sil 910 is an alternative to Silastic HS. This material is a two component silicone rubber compound that will need careful measuring of its components. It has a relatively high tear strength and excellent working properties. 910 cures to a soft, pliable hardness and will reproduce the finest detail. Vacuum degassing is usually not necessary if care is taken during the mixing and pouring phase. Although not required, remember that deairing of all silicone rubber compounds is recommended to eliminate any entrapped air. Deaired molds produce smoother molds due to the lack of trapped air bubbles that form along the contact surface of the piece being reproduced. This material cures at room temperature with negligible shrinkage. It is suitable for making molds to cast wax, casting plaster, resins, epoxies and low melt alloys. Smooth-Sil 910 can be thickened with the optional THI-VEX thixotropic additive.

Smooth-Sil THI-VEX is a thixotropic additive that will thicken the silicone so that it can be used for brush-on applications. Brush-on applications are ideal for vertical and overhead surfaces such as architectural elements that cannot be removed from the structure. This additive is only for use with Smooth-Sil 910.

Smooth-Sil Accelerator is an additive that will speed up the curing time of any of the above Smooth-On silicone rubber compounds. Remember that speeding up any cure times of silicone rubbers with an accelerator can cause decreased mold life and flexibility.

Silicone Cat Ratio R/C Working Cure Tear Viscosity cps

Type Type By Weight Time Time Strength Hardness Shore A

900 --- 1:1 90 min 16 hrs 15 4,500 / 35

910 --- 100:5 90 min 24 hrs 60 20,000 / 18

Cat No. Description Price

CA-24900-002 Smooth-Sil 900, 2 Pint (2 lb) Kit $ 25.00

CA-24900-020 Smooth-Sil 900, 2 Gal (20 lb) Kit 126.00

CA-24910-002 Smooth-Sil 910, 1 Quart (2.1 lb) Kit 25.00

CA-24910-010 Smooth-Sil 910, 1 Gal (10.5 lb) Kit 99.23

CA-24950 Smooth-Sil Accelerator, 1/2 oz. 18.00

CA-24975 Smooth-Sil Thixotropic, 1 Pt. 15.00

molding Caulk

Reprosil

Reprosil is a heavy body hydrophillic vinyl polysiloxane high definition impression material. It comes packed in two 90ml tubes for a total of 180ml (approximately 6 oz.). Each tube is about the size of a large tube of toothpaste. Reprosil is used most often for surface detail reproductions. Its’ heavy body consistency means it can be hand molded and applied without the need of forms or dams. It has an easy 1:1 mixing ratio and a very short setting time of only 4-1/2 minutes. Reprosil is ideal for projects that need a quick turn around time. One caution when working with Reprosil, latex gloves will interfere with the setting reaction. If gloves are to be worn, N-Dex Nitrile gloves are a good alternative. You might already be familiar with Reprosil but not by name, it has a very distinctive orange color.

Cat. No. Description 1-5 Pks 6 + Pks

CA-26100 Reprosil-Caulk, 180ml Kit $ 38.50 $ 36.20

modeling Clay

Klean Klay

Klean Klay is a non-drying, non-hardening, no-sulfur modeling clay ready for use in a variety of applications. It is tan in color, and has a smooth, firm consistency to retain the shape into which it is molded. It is easily hand-pliable at room temperature making it easy to work with and shape. Klean Klay is a suitable mold-making material for RTV silicone rubber molding. We stock regular consistency in 1/4 lb. sticks. It is packed 4 sticks to a 1 pound pack, 20 sticks to a 5 pound pack and 80 sticks to a 20 pound pack.

Cat. No. Description Price

CA-18110-001 Klean Klay, Reg., 1 lb $ 2.25

CA-18110-005 Klean Klay, Reg., 5 lbs 10.13

CA-18110-020 Klean Klay, Reg., 20 lbs 36.00

Roma Plastalina Clay

Roma Plastalina Clay is one of the world’s finest modeling materials that is permanently pliable. We stock four grades of consistency. Roma Plastalina Clay comes in 2 lb. blocks in a Gray-Green color.

Cat. No. Description 1-4 Blk 5 + Blk

CA-14105 Roma Plastalina Clay, Soft $ 6.54 $ 5.03

CA-14110 Roma Plastalina Clay, Med. 6.54 5.03

CA-14115 Roma Plastalina Clay, Med. Firm 6.54 5.03

CA-14120 Roma Plastalina Clay, Firm 6.54 5.03

Modeling Wax

Sheet Wax

Sheet wax is a thin sheet of wax measuring 6" x 3" x 1/16". It is ideal for making surface impressions. When lightly heated, the thin sheet becomes pliable and easily molds to most any shape. Once cooled, it will hold its shape. Each package contains 16 sheets.

Cat. No. Description Price.

CA-22000 Sheet Wax, 6" x 3" x .050" $ 9.92

Hydrocal (Casting Plaster)

General Information About Casting Media

Plaster of Paris and most casting plasters are great for casting toy dinosaurs, handprints and crafts at home and school for your kids, but the professional conservator needs are for a much higher quality product like Hydrocal. You will find that most casting materials mix at a ratio of upwards to 100 parts water to 100 parts plaster, this can cause any number of problems when crafting larger casts. The great quantities of water held in large casts needs to be driven off before the cast can be worked or obtain its maximum hardness and strength. The drying process at room temperature, can easily take days, weeks, even a month. Due to this long drying time, the finished cast will have at best, half its potential strength. If dried to quickly, the cast can easily warp, distort and or generate stress cracks that will sooner or later cause the cast to fail.

Listed below you will find Hydrocal casting media that we have selected to offer conservators. Our Hydrocal is specifically designed to eliminate these and many other problems that can arise from casting small losses to the largest of reproductions.

Tuf Cal Plaster

Tuf Cal Plaster is a polymer modified, fibered plaster that provides strong, durable cast. This formulation produces casts with good compressive strength (4,300 psi), and good impact/chip resistance. Tuf Cal Plaster has a working time of 27-37 minutes, can be removed from a mold in as short as 15-20 minutes after setting and can accept paints, stain and other surface treatment in as little as 2 to 4 hours after set. It will reproduce fine detailed casts from molds made of silicone, latex, urethane and most other molding materials. The mixing consistency is achieved with a moderate water content, 50 parts of water to 100 parts of Tuf Cal Plaster. Once hardened it can be drilled, filled, carved and painted. Dries to a hard, white, smooth finish. It comes in 1, 4, and 25 lb. bags.

Cat. No. Description Price

CA-20105-001 Tuf Cal Casting Plaster, 1 lb $ 00.00

CA-20105-004 Tuf Cal Casting Plaster, 4 lbs 00.00

CA-20105-025 Tuf Cal Casting Plaster, 25 lbs 00.00

DryStone Casting Media

DryStone Casting Media is a fast-casting material that provides strong, durable cast without the need of long drying times. It is a high-strength formulation that produces casts with excellent compressive strength (an impressive 10,000 psi) and good impact resistance. DryStone has a working time of 5-10 minutes, can be removed from a mold in as short as 15-20 minutes after setting and can accept paints, stain and other surface treatment in as little as 2 to 4 hours after set. It will reproduce fine detailed casts from molds made of silicone, latex, urethane and most other molding materials. The key to this material is that its mixing consistency is achieved with very little water, only 18-20 parts of water to 100 parts of DryStone. Once hardened, it can be drilled, filled, carved and painted. Dries to a hard, white, smooth finish. It comes in 1, 4, and 25 lb. bags.