POLY-SIL MOLD RUBBERS: AT A GLANCE

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1 3 RTV s Poly-Sil RTV Liquid s The Poly-Sil RTV Liquid s each consist of a Part A and Part B, which, after mixing, cure at room temperature to flexible, high-strength, mold rubbers. Poly-Sil s make molds that are easy releasing and stable at higher temperatures. They are excellent for casting plasters, waxes, cements, low melting metals and many resins such as epoxies, polyesters, urethanes and acrylics. As with other Polytek elastomers, the last two digits in the product name indicate the approximate Shore A hardness of the cured rubber. Poly-Sil rubbers range in hardness from a very soft A10 to a firm A60. MODEL PREPARATION Porous models such as wood or plaster should be sealed to prevent penetration of the rubber into the pores of the material. Wax, petroleum jelly, lacquer, paint and most other coatings are suitable sealers. Materials that will contact the rubber can be sprayed or coated with a light coat of Pol-Ease 2350, which functions as a sealer and release agent. Allow the Pol-Ease 2350 to dry before applying liquid rubber. -based release agents (i.e., Pol-Ease 2300) are not to be used on surfaces that contact liquid Poly-Sil rubbers since inhibition and/or adhesion may occur. In addition, modeling clays containing sulfur may inhibit curing. In every case where there is any question about the compatibility between the rubber and the prepared model surface, a test cure should be made on an identical surface to determine that complete curing and good release are obtained. Poly-Sil rubbers may bond to cured silicone rubbers unless a parting agent is used. Porous models must be vented from beneath to prevent trapped air from forming bubbles in the rubber (see p. 12). MIXING AND CURING Before mixing rubber, be sure that both Parts A and B are at room temperature and that all tools and models are ready to go! Check product labels or technical bulletins to determine working time for the product -- some products set fast -- meaning that you must work quickly. Many Poly-Sil Part As require stirring before use. If there is a Stir Before Use label on the container -- be sure to do so. Molds made from highperformance Poly-Sil rubbers are best for casting harsh resins. This gargoyle blanket mold made of soft PlatSil easily pulls off the cast resin part. The smooth, release-free demold of silicone is especially welcome on highly detailed parts. POLY-SIL MOLD RUBBERS: AT A GLANCE TinSil 70 Series - Tin-catalyzed silicone systems that cure to tough, high-performance rubbers with easy release properties and resistance to high temperatures. Great for casting polyester resin. PlatSil 71 Series - High-tear strength, platinum-cured silicone systems with hardness up to A40. Excellent for casting polyurethane resins and dimensionally accurate prototype parts. PlatSil 73 Series - High-tear strength, tough, platinumcured silicone systems with hardness up to A60. Excellent for casting polyurethane foams and dimensionally accurate prototype parts. PlatSil Gel 10 - A soft, translucent rubber for delicate casting projects and special effects applications Mix Ratios Vary! Check the mix ratios for the specific product you are using. For Poly-Sil rubbers, most mix ratios are expressed by weight. Carefully weigh Parts A and B in proper ratio. Accurate weighing is essential to obtain optimum physical properties from the cured rubber. Weigh Part B into a clean metal or plastic mixing container. Then weigh the appropriate amount of Part A into the same container. Mix thoroughly, scraping sides and bottom of the container. Hand mixing with a Poly Paddle (see p. 62) is best to avoid mixing air into the rubber. To ensure a bubble-free mold, deaerate the liquid rubber under vacuum at inches mercury until the mass of rubber rises and then collapses. Deaerate for an additional 2 minutes. For vacuuming, use a mixing container 3 to 4 times larger than the volume of rubber. Pour the rubber as soon after mixing as possible for best flow and air bubble release. If reinforcement of the rubber is needed (i.e., in thin blanket molds), place stretchy, open mesh nylon or dacron cloth into the uncured rubber. Be sure that the fabric is not too close to the mold surface or the weave of the cloth may show through to the face of the mold. Check product labels or technical bulletins to determine cure times. To reach full hardness in the specified demold time, temperature should be above 77 F (25 C). At lower temperatures, more time may be needed to reach full hardness. Curing below 65 F (18 C) is not recommended. For most Poly-Sil products, final cure properties are obtained in about seven days, but most molds may be used with care after curing for 24 to 48 hours. USING THE MOLD No release agent is necessary for casting most materials in Poly- Sil molds. For longer mold life, however, a barrier coat or release agent (i.e., Pol-Ease 2300) is recommended when casting epoxy, polyurethane or polyester resins. Most Poly-Sil molds can be 40 (610) (800)

2 RTV s 3 stored for years, but tin-catalyzed silicone molds eventually deteriorate and lose their elasticity. ADDITIVES & ACCESSORIES Polytek offers various additives that can be used to vary the properties of the cured and uncured Poly-Sil rubbers. Thinner/Softener - Very low viscosity 50 cst Fluid can be added sparingly to the mixed rubber to thin the mix with some loss of strength, hardness and cure speed. More than 10% fluid addition may exude from the cured rubber. Accelerator - A specially formulated accelerator can be added to most Poly-Sil products to reduce the cure time. Thickener - Specially formulated chemical thickeners can be added to most Poly-Sil products to make the liquid rubber thicker (i.e., for brush-on application). Cab-O-Sil Fumed Silica, which is both a thickener and thixotropic agent, can also be added to mixed Parts A and B in order to form a gel appropriate for application by brush or trowel. Colors - Certain Poly-Sil rubbers can be tinted to various shades by adding small amounts of colors. Barrier Coat - A barrier coat (i.e., Barrier PF) is a fast drying, lacquer-like primer that is sprayed into a silicone mold and allowed to dry prior to pouring plastic. The plastic cures against the barrier coat and comes out on the plastic casting resulting in a pre-primed part. Using a barrier coat may extend mold life. To learn more about additives, refer to product technical bulletins or call Polytek Customer Service. See additives and accessories for Poly-Sil products in the box to the right. CLEAN UP Tools should be wiped clean before the rubber cures. Denatured ethanol is a good cleaning solvent, but it must be handled with extreme caution owing to its flammability and health hazards. SAFETY Before use, read product labels and Material Safety Data Sheets. Follow safety precautions and directions. Contact with uncured products may cause eye, skin and/or respiratory irritation. Avoid contact with skin and eyes. If skin contact occurs, remove with waterless hand cleaner or alcohol then soap and water. In case of eye contact, flush with water for 15 minutes and call a physician. Use only with adequate ventilation. Poly-Sil products are not to be used where food or body contact may occur. STORAGE LIFE At least six months in unopened containers stored at room temperature (60-90 F). TINSIL & PLATSIL ACCESSORIES Pol-Ease 2300 Release Agent 12-oz can, case of 12 cans Pol-Ease 2350 Release Agent 1 qt (1.5 lb), 5 gal (26 lb) PlatThix For Thickening PlatSil Rubbers 4 oz, 1 pt (1 lb) Fluid 50 cst Grade For Thinning Poly-Sil Rubbers 1 qt (2 lb), 1 gal (8 lb), 5 gal (40 lb) TinSil FastCat 4 oz, 1 pt (1 lb), 1 gal (8 lb) TinThix 4 oz, 1 pt (1 lb) PlatSil 71/73X Accelerator 4 oz, 1 pt (1 lb), 1 gal (8 lb) PlatSil 71R Retarder 4 oz, 1 pt (1 lb), 1 gal (8 lb), 5 gal (40 lb) Barrier PF 1 qt (1.5 lb), 5 gal (35 lb) Cab-O-Sil 5 gal, 1 bag (10 lb) CAUTION! -- Certain chemicals cause cure inhibition in silicone rubbers. Beware of amines, polyesters and tin compounds with PlatSil systems. Sulfur compounds can affect both PlatSil and TinSil systems. Perform a test cure! Poly-Sil rubber blanket molds reproduce the fine details of models and are soft and tough enough to easily pull off complex castings. Usually, the more intricate the model/casting, the softer the mold rubber selected. This very ornate column capital was easily cast in TinSil The gargoyle mold was made using PlatSil The large, multi-piece, Ronald McDonald mold was made using TinSil to cast numerous polyester resin parts. 41

3 3 RTV s TinSil 70 Series DESCRIPTION: TinSil 70 Series RTV Rubbers are condensation-cure, tin-catalyzed, flexible mold rubbers. TinSil products consist of a liquid Part B base and Part A accelerator, which, after mixing at the proper ratio by weight, cure at room temperature to rubbers with tough, knotty tear properties. TinSil molds have easy release properties and high temperature resistance. TinSil molds are excellent for casting polyester, epoxy and polyurethane resins, as well as for waxes and other materials where release-agent-free casting is needed. TinSil is the softest system and is used for very delicate castings. TinSil is Polytek s most popular and versatile mid-range hardness silicone rubber. TinSil is firm and has excellent tear properties making it popular for casting polyurethane forms and plastic prototype parts. TinSil is stable at higher temperatures making it suitable for casting low melting metals. As a result of its high hardness, TinSil has limited tear strength. MIXING AND CURING: See p. 40. CAUTION! TinSil products release alcohol while curing. Alcohol can inhibit the surface cure of some polyurethanes. Before casting polyurethanes in a TinSil mold, alcohol can be evaporated by letting the mold sit in a warm location for 24 hours or by baking the mold for 4 hours at ~200 F. This loss of alcohol results in slight shrinkage of the rubber during cure (up to 1%). In cases where slight shrinkage cannot be tolerated, consider PlatSil rubbers. USING THE MOLD: See p. 40. [Note: Molds made with excess catalyst may be subject to faster degradation on aging.] ACCELERATING CURE SPEED: Use TinSil FastCat in place of any TinSil Part A in order to accelerate cure and shorten demold time. When using FastCat the working time is shorter, so care must be taken to avoid over-catalyzing. FastCat can be used in a range of 2-6 parts per 100 parts B. At 2 parts FastCat to 100 parts B, the working time and demold time is similar to that observed when using 10 parts of the appropriate TinSil Part A. At 3 parts FastCat per 100 parts B, the working time is reduced to ~20-30 minutes, with <8 hour demold. Experiment with a small mix first to determine the best amount of FastCat to use. Use of FastCat can shorten the library life of cured TinSil rubber. THICKENING FOR BRUSH ON: TinSil 70 Series rubbers can be thickened with TinThix liquid thickener or with Cab-O-Sil for brushing on a blanket mold. TinThix is a liquid additive that can be mixed into the Part B (before mixing with Part A) to achieve varying levels of thixotropy Mix Ratio (By Weight) 1A:10B 1A:10B 1A:10B 2A:100B 1A:10B 5A:100B Hardness, Shore A Pour Time (min) Demold 77 F (hr) Color Blue Blue Blue Beige Blue Red Mixed Viscosity (cp) 10,000 10,000 14,000 26,000 25,000 17,000 Specific Volume (in 3 /lb) Specific Gravity Shrinkage Upon Cure (%) ~0.3 ~0.3 ~0.3 ~0.3 ~0.3 ~0.8 Product Unit Weight Size Net Weight (lb) (lb) A B A B TinSil 70-10, 70-20, oz 1 pt , pt 1 gal Mix Ratio 1A:10B /2 gal 5 gal gal 55 gal TinSil oz 1 pt Mix Ratio 2A:100B oz 1 gal pt 5 gal gal 55 gal TinSil oz 1 pt Mix Ratio 5A:100B 8.4 1/2 pt 1 gal qt 5 gal gal 55 gal (610) (800)

4 RTV s 3 PlatSil 71 Series DESCRIPTION: PlatSil 71 Series RTV Rubbers are two-component, addition-cure, platinum-catalyzed, flexible mold compounds. The 71 Series products exhibit a tough, knotty tear, making them especially valuable to the mold making industry. They are excellent mold materials for casting polyester, epoxy and polyurethane resins, as well as for waxes and many other materials. PlatSil 71 Series products offer advantages over tincatalyzed systems in certain applications because on curing they don t shrink and don t produce alcohol (like tin-catalyzed silicones) which can inhibit urethane castings. MIXING & CURING: See p. 40. USING THE MOLD: See p. 40. ACCELERATING CURE SPEED: Accelerate the cure with heat or the addition of PlatSil 71/73X. Mix 71/73X with Part B prior to adding Part A. Weigh and add Part A to the accelerated Part B mixture and mix thoroughly. Pour over a properly prepared model as soon after mixing as possible. The addition of 1 part 71/73X per 100 parts of Part B decreases the gel time to ~1/3 the normal gel time. The addition of 2 parts decreases the normal gel time to ~1/4. The addition of 3 parts decreases the normal gel time to ~1/6. Experimentation on a small scale is recommended before making a larger mix. FEATURES Easy mix ratios; some 1:1 mixes available Cure at room temperature or accelerate with heat Easy release properties -- save on release agents High tear strength -- fewer prematurely torn molds Good chemical resistance for longer mold life Low/zero shrinkage for better dimensional reproduction Range of hardnesses from A10 to A40 RETARDING CURE SPEED: PlatSil 71R added to PlatSil Part A prior to mixing with Part B slows the cure yielding longer working time and longer demold time. Adding ~1% of 71R to the total mixed weight of PlatSil A+B roughly doubles the working time. Adding ~2% of 71R triples working time. Do not use more than 4% as the system may not cure at all. THICKENING FOR BRUSH ON: Thicken PlatSil 71 Series rubbers by adding PlatThix or Cab-O-Sil for brush-on blanket molds. When brushing PlatSil or 71-20, apply subsequent coats to the previous layer within one hour to obtain best adhesion Mix ratio, by weight 1A:10B 1A:1B 1A:1B 1A:10B 1A:10B 1A:5B Hardness, Shore A Pour Time (min) Demold Time 77 F Color Pink Blue Green Lt. Purple Lt.Green Blue Hazy transparent Mixed Viscosity (cp) 3,500 15,000 12,000 25,000 15,000 25,000 Specific Volume (in 3 /lb) Specific Gravity Shrinkage Upon Cure Nil Nil Nil Nil Nil Nil Product Unit Weight Size Net Weight (lb) (lb) A B A B PlatSil 71-15, pt 1 pt Mix Ratio 1A:1B gal 1 gal gal 5 gal PlatSil 71-10, 71-30, oz 1 pt Mix Ratio 1A:10B pt 1 gal /2 gal 5 gal gal 55 gal PlatSil qt 1 gal Mix Ratio 1A:5B gal 5 gal x 6 gal 55 gal

5 3 RTV s PlatSil 73 Series DESCRIPTION: PlatSil 73 Series RTV Rubbers are two-component, addition-cure, platinum-catalyzed, high tear strength, flexible mold compounds. The 73 Series rubbers are recommended for evaluation as mold materials for polyester, epoxy and polyurethane resins, as well as for waxes and many other materials. PlatSil 73 Series silicones offer advantages over tin-catalyzed systems in certain applications because on curing they don t shrink, they don t produce alcohol (like tin-catalyzed silicones) which can inhibit urethane castings, and they can be heat accelerated to speed the cure. MIXING & CURING: See p. 40. USING THE MOLD: See p. 40. ACCELERATING CURE SPEED: Accelerate the cure with heat or the addition of PlatSil 71/73X. Weigh and add 71/73X to Part B and mix. Weigh and add Part A to the accelerated Part B mixture and mix thoroughly. Pour over a properly prepared model as soon after mixing as possible. Demold when tack free. The addition of 1 part 71/73X per 100 parts of Part B decreases the gel time to ~35 min. The addition of 2 parts decreases the gel time to ~30 min. The addition of 3 parts decreases the gel time to ~25 min. The addition of 71/73X softens the cured rubber FEATURES Low viscosity for excellent detail reproduction and easy degassing. Easy 10A:100B mix ratio -- can use with dispensing machines Cure at room temperature or accelerate with heat Easy release properties -- save on release agents High tear strength -- fewer prematurely torn molds Good chemical resistance for longer mold life Low/zero shrinkage for better dimensional reproduction Range of hardnesses from A30 to A60 slightly. Remember, heat accelerates the cure; low temperatures slow the cure. THICKENING FOR BRUSH ON: PlatSil 73 Series rubbers can be thickened with PlatThix liquid thickener or with Cab-O- Sil for brushing on a blanket mold Mix Ratio, By Weight 10A:100B 10A:100B 10A:100B Hardness, Shore A Pour Time (min) Demold 77 o F (hr) Color White Green Blue Mixed Viscosity (cp) 15,000 35,000 40,000 Specific Volume (in 3 /lb) Specific Gravity Shrinkage Upon Cure Nil Nil Nil PlatSil 73-29, 73-45, Mix Ratio 10A:100B Unit Weight Containers (lb) Size Net Weight (lb) A B A B oz 1 pt pt 1 gal gal 5 gal (73-29) 6 gal 55 gal gal 55 gal (610) (800)

6 RTV s 3 DESCRIPTION: PlatSil Gel-10 is a colorless, translucent, two-part, liquid, RTV silicone system, that rapidly cures at room temperature to a soft (~A10), tough rubber within 30 minutes after mixing Parts A and B. PlatSil Gel-10 has an easy 1:1 mix ratio. PlatSil Gel-10 does not shrink on curing and may be used as a flexible mold material for delicate casting projects and to create special effects. MIXING AND CURING: See p. 40. Normal mixes will gel in approximately 6 minutes at room temperature; faster if warm, slower if cold. Thus, the mix should be immediately placed over the model or in the mold. There is not normally adequate time for vacuum (unless retarder is used), but pressure casting may be useful to eliminate bubbles. Contamination with soaps, amines, sulfur, tin compounds and some RTV Rubbers may inhibit surface cure. USING THE MOLD: For best results, allow PlatSil Gel-10 to cure for at least 1 hour before it is put into use. No release agent is necessary for casting most materials in properly cured PlatSil Gel- 10. For longer mold life, however, use a barrier coat or release agent when casting epoxy, polyurethane or polyester resins. ACCELERATING CURE SPEED: PlatSil 71/73X can be mixed into Part B prior to adding Part A to accelerate gel time and cure. Weigh and add 71/73X to Part B and mix. Weigh and add Part A to the accelerated Part B mixture and mix thoroughly. Pour over a properly prepared model as soon after mixing as possible. Demold when tack free. The addition of 1 part 71/73X to 100 parts of Part B decreases the gel time to 1/3 the normal gel time. The addition of 2 parts decreases the normal gel time to 1/4. The addition of 3 parts decreases the normal gel time to 1/6. RETARDING CURE SPEED: Adding PlatSil 71R to PlatSil Part A prior to mixing with Part B will slow the cure yielding longer working time and longer demold time. Adding 71R at 1% of the weight of total mix (A+B) will roughly double the working time. 2% will triple working time. 5% will yield a 60- minute work time with a fast, 120-minute demold time. Never use more than 5% since the system may not cure at all. PlatSil Gel-10 FEATURES Soft (~A10), translucent, silicone rubber Easy 1:1 mix ratio Fast 30-minute demold with 6-minute work time PlatSil 71R Retarder slows the cure PlatSil 71/73X Accelerator speeds the cure PlatThix thickens the mix to a brushable paste Bonds to Poly Plastics THICKENING FOR BRUSH ON: Thicken with PlatThix liquid thickener or with Cab-O-Sil for brush-on application. Add 2% PlatThix to the total mix weight for a light-bodied, non-sag gel. BONDING TO PLASTICS: PlatSil Gel-10 bonds to clean, cured Poly 15 Series plastics that are less than 24-hours old. Poly 15 Series plastics bond to PlatSil Gel if poured into the PlatSil Gel while it is still tacky (less than 30-minutes old). Each bonding procedure should be tested prior to use in production scale. Remember, release agents on any surface can interfere with good bond development. David Gavin and colleagues from Arran Studios in Cork, Ireland, proudly display their Velociraptor casting made with life-like PlatSil Gel-10 skin. PlatSil Gel-10 makes great animatronic skins. The product can be softened with the addition of Fluid and colored to make the look and feel just right. Mix ratio, by weight 1A:1B Hardness, Shore A Pour time, minimum 6 min Demold 25 C (77 F) 30 min Color Colorless Viscosity, mixed 15,000 cp Specific volume (in 3 /lb) 25 Specific 25 C (77 F) 1.10 Shrinkage upon cure Nil Mix Ratio: 1A:1B (By Volume) Unit Weight Containers (lb) Size Net Weight (lb) A B A B pt 1 pt gal 1 gal gal 5 gal gal 55 gal