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EDUCATION RESOURCES

Moldmaking

Quantum Silicones produces two systems of Moldmaking materials – Addition cure (platinum catalyzed) and Condensation cure (tin catalyzed).  Please refer to the technical data sheet corresponding to your product of choice to determine which system is recommended for your application.  Features of each chemistry are listed below.

Moldmaking supplies needed: gloves, mixing containers, stirring sticks, a gram scale and a mold box.  A brief summary of common mold boxes is listed.

Commonly Used Moldmaking Terms:

RTV: Room Temperature Vulcanization (room temperature cure).

Viscosity: Describes the consistency of a liquid and is reported in centipoises (cps). Thinner liquids will report a lower number; and thicker liquids will report higher numbers.  For example, water has a viscosity of 1.0 cps, while chocolate syrup will measure higher at approximately 1,000 cps. Catalyzed viscosities of QSi’s moldmaking silicones will range between 7,500 and 105,000 cps.

 

Durometer: This property can be measured with a durometer gauge. This gauge has a needle which is pushed into the rubber.  The further the needle is able to penetrate into the rubber, the lower the reading.  The Shore A scale is used for reporting the durometer of most molding rubbers.  The scale of measurement is 0 to 100. Softer rubber will result in a low reading; and harder rubber will result in a higher reading. The durometer requirement of your silicone is dependent upon your applications.

 

Pour Time, Working Time or Gel Time: These properties refer to how much time the user will have before the material begins to gel. Your pour should be completed well before the end of this time to ensure both a good flow into the details of the mold, and to allow any air bubbles to rise to the surface.

 

Pot Life: The time it takes a catalyzed material, once mixed, to double in viscosity. A viscometer is used for this test. An initial viscosity reading is taken and a time is documented. When viscosity has doubled, the time is recorded.

 

Demold Time:  The recommended time in which a cured part can be removed from the mold, if the mold was cured at room temperature.

 

Cure Time: Even though a product can be demolded and feels cured, the curing process may continue for up to one week.

 

Linear Shrinkage: The reduction in size, which a user may experience, during the life cycle of a silicone mold.  The shrinkage is due to the release of a cure byproduct in condensation cure systems, as well as “oils” drawn out of the mold by aggressive casting resins. QSi’s addition cure products are noted for their low shrinkage.

 

Tear Strength: The measurement of force required to tear a rubber.

 

Inhibition: The result of a poisoning of the cure catalyst that stops the cross linking necessary for the silicone to properly cure.  The result of inhibition is tackiness at the pattern interface or a total failure of the silicone to cure.

 

Addition Cure Inhibition: Materials known to inhibit cure are sulfur-containing modeling clays, natural rubber such as latex and rubber gloves, masking tape, amine or sulfur-containing material and condensation cure (tin-catalyzed) silicones.

 

Condensation Cure Inhibition:  Not a common occurrence.  Some sulfur containing modeling clays can slow the cure of condensation RTVs.  However, the condensation cure RTV will eventually cure when the clay is removed.

Inhibition can be avoided by applying a barrier coat before silicone is applied to the model.

Four Common Types of Molds:

Block Mold: One piece without the negative drafts of undercuts.  This is probably the easiest mold to produce.  The original part should be placed in the box so the silicone is able to flow around it.  If the part is simple, it can be placed in a plastic cup, a disposable plastic container or a wooden box (pine wood not recommended).  If you choose a wooden box, be sure to seal it properly if it appears to be porous.

 

Block Mold – Multiple Piece: Made exactly like a block mold and simply cut in half once it cures to remove the part.  If you prefer not to cut the mold, partially fill the container and allow it to cure. Then, apply a thin layer of release agent and finish pouring the mold.  Once the second layer is cured, the mold should easily separate.

 

Glove Mold – Brushed onto the Pattern: Requires a thixotropic agent which allows the silicone to be brushed on an original piece without running off the surface.  The thixotropic agent can be mixed in the catalyst or as a separate additive.  This type of silicone is ideal for building restoration.  The silicone can be brushed on an original piece of crown molding, allowed to cure and then be removed.  The mold can then be cast to produce replications of the original molding.  This type of molding is also becoming popular to cast rocks or stones to create molds of faux rocks, rock climbing walls, side walks and props for theme parks.

 

Cast Glove Mold: Made by creating a void around the original part in a consistent thickness.  This method is usually accomplished by forming modeling clay around the pattern and then forming a hard shell around the clay.  The shell can be made by using either fiberglass, urethane or plaster.  After the shell has cured, the clay is removed to create a void which can be filled by silicone.

 

Potting & Encapsulating Silicones

Quantum Silicones’ Potting and Encapsulating products are used to provide a flexible, protective barrier against a variety of environmental factors.  Silicones are used in a wide array of applications – typically electronics – to provide excellent electrical properties as well as protection against moisture, debris, heat shock and vibration.

 

These two-component potting compounds and silicone encapsulants are generally used when a deep section cure is required.  They can be cured at either room temperature or accelerated with heat and are also available in a wide range of viscosities.  QSi’s two-component encapsulants can also be either machine or hand dispensed.  Once cured, its hardness can range from a gel-like consistency to a hardened rubber.

 

Quantum Silicones’ Potting and Encapsulating series are used for many generic applications, but were also  developed for specific applications requiring optical clarity, thermal conductivity, flame resistance, UL rated or extreme service temperatures (-55C to 204C).

 

Silicone Gels

QSi’s line of Silicone Gels offers a broad range of physical properties to benefit your specific needs.  Silicone Gels are used in numerous applications when a soft and highly flexible encapsulation is required.  Gels provide the same protection as standard silicone potting and encapsulants as well as protection against extreme shock and vibration.   Silicone Gels also provide excellent protection against moisture, debris, heat, and harsh environmental factors.

 

QSi’s Silicone Gels are available in a variety of hardnesses, penetrations and viscosities.  Low viscosity gels can be easily dispensed into intricate areas and thixo-gels can be applied where non-slumping or sagging is required.   Silicone Gels typically provide a primerless, “pressure sensitive” type bond to most substrates.  However, adhesion can be further enhanced with the use of QSi’s primers.

 

Silicone Gels are two-component, addition (platinum) curing products with most having a one-to-one mix ratio.  They can be cured at either room temperature or heat cured and can also be dispensed either automatically or by hand.  The majorities of QSi’s silicone gels are clear, but can be colored or tinted for visual identification. Customizable properties in QSi’s silicone gels include:

  • Refractive index
  • Useful temperature range
  • Adhesion
  • Cure speed
  • Color / Tint
  • Penetration
  • Viscosity
  • Conductivity

 

Architectural

Many different architectural elements can be created or restored by using QSi’s moldmaking silicones to create molds of wood, columns, cornices, and pavers. A wide variety of faux wall surfaces, like stone and brick can be made by using silicone molds. These silicones feature high tear strengths that contribute to the durability of the mold.
 

 

Power Supplies

Various forms of silicone materials from QSi are designed to protect power supplies from thermal stress and help maintain their original properties in high voltage functions. These flexible compounds from QSi can be used to coat wires, provide insulation for transformers and protect electronic controls.

Benefits of QSi’s Silicone Technology:

  • Moisture protection
  • High thermal conductivity grades available
  • Repairable
  • UL listed grades are available (See our UL Rating File Number QMFZ2.E205830)
  • Low modulus materials minimize CTE strain
  • Low viscosity for fast dispensing
  • Self-bonding capabilities

 

Automotive / Transportation

Silicone compounds provide long-lasting durability and protection for interior, exterior and underhood mechanisms designed for automotive applications. These silicone compounds from QSi can increase safety as well as improve performance.

Benefits of QSi’s Silicone Technology:

  • Extreme low and high temperature stability
  • Chemical and flammable resistance
  • Thermally conductive grades for heat management
  • Environmental protection
  • Electronic sensor packaging and protection
  • Strong adhesion to a wide variety of substrates with use of a primer

 

Aerospace

Aerospace applications require demanding physical properties for all sealants or encapsulants. Potting and encapsulating materials as well as silicone gels by QSi can perform at either extremely low or high temperatures, providing environmental protection while maintaining their physical properties.

Benefits of QSi’s Silicone Technology:

  • Moisture protection
  • Excellent shock and vibration resistance
  • Room temperature and heat curing adhesion packages for multiple substrates
  • Products with low temperature capabilities down to -110C
  • Low volatile materials are available, ASTM E-595
  • Optically clear technology available
  • Flame retardant, UL listed grades available (See our UL Rating File Number QMFZ2.E205830)

 

LED Lighting

Temperature resistant, optically clear silicones can be applied over surface mount LEDs and are designed to be mixed with either diffusants or whitening agents if required. QSi has a wide variety of potting compounds and sealants used in the LED industry that can bond substrates, protect electronics and provide thermal stability.

Benefits of QSi’s Silicone Technology:

  • Environmental protection
  • Higher refractive indices to facilitate a brighter and longer lasting light
  • Non-yellowing catalyst systems are available
  • Low viscosity to flow around complex parts and minimize air entrapment
  • Excellent thermal stability
  • Self-bonding grades available
  • UL listed grades available (See our UL Rating File Number QMFZ2.E205830)

Prosthetics

QSi offers translucent silicone grades in the Moldmaking series that are pigmentable. These materials are durable, but soft, and can feature a realistic look and feel of skin.
 

Connectors

QSi’s silicone gels are used as durable encapsulants in high-performance electronic connector systems. These soft silicone gels protect leads inside the connectors from environmental contamination. Additionally, silicone gels by QSi have excellent resistance to thermal cycling, vibration and mechanical shock, and will reseal throughout multiple insertions.

Benefits of QSi’s Silicone Technology:

  • Moisture protection
  • Self-healing properties
  • Withstands thermal cycling
  • Non-slumping, thixotropic grades are available
  • Room temperature primerless adhesion
  • Corrosion resistant
  • Flame retardant, UL listed grades available (See our UL Rating File Number QMFZ2.E205830)

 

Candles & Soap

QSi has some of the softest and most flexible moldmaking rubber used to make delicate and intricate soap and candle molds. Moldmaking siilicones with a low modulus are tough and plyable for easy demolding.
 

Prototyping

Prior to your project going into production, QSi’s moldmaking materials enable you to build a physical, three-dimensional representation of your new idea. Silicones by QSi exhibit excellent mechanical properties, dimensional accuracy, high temperature resistance and a non-stick surface.
 

Special Effects

Whether you are creating a life-sized dinosaur or a full body cast, QSi’s Moldmaking silicones are used in both large-scale productions and in hobbyists’ projects. Choose from a wide selection of easy-to-use, pigmentable and affordable products to create props for the motion picture and theme park industries.

Also developed for special effect applications, QSi offers a selection of silicone gels that are tacky by design and can be used to temporarily adhere special effects prosthetics/makeup to skin or props. These robust silicone gels can also function as cushioned external prosthetics placed on the actor or prop.

Benefits of QSi’s Silicone Technology (Silicone Gels):

  • Pigmentable
  • Low viscosity for easy dispensing
  • Wide range of penetrations
  • Removable and reusable
  • Remains tacky even when exposed to moisture

Sculpture, Statuary, Figurines

QSi’s Moldmaking silicones allow you to create an exact replica of your original artwork. With multiple catalyst options, the rheology (flow properties) our moldmaking materials can be easily altered, allowing convenient application to upright figures. Once mixed, our silicones can be brushed, sprayed or poured onto the master model.

Solar / Renewable Energy

QSi’s silicone encapsulants and sealants offer environmental and long-term protection to meet the demands of solar panel applications.

Benefits of QSi’s Silicone Technology:

  • Optically clear and non-yellowing systems are available
  • UV resistant encapsulating grades can out-perform the durability of organics
  • UL Rated, Flame retardant potting grades for junction box applications
  • Corrosion resistant
  • Primerless adhesion to a wide variety of plastics
  • Thermally conductive grades for heat management

Electronics

Properties in QSi’s potting and encapsulating line provide a protective barrier against moisture and environmental contaminants.

Benefits of QSi’s Silicone Technology:

  • Low viscosity products allow for easy pouring and potting around complex parts
  • Conductive technology for thermal management
  • High durometer with low modulus technology is available to minimize CTE strain
  • Excellent shock and vibration resistance
  • Variety of both room temperature and heat curing materials
  • Adhesion packages are available to obtain primerless adhesion to many substrates
  • Withstand extreme temperatures from -55C to 204C (Customized temperature ranges
    are available from -110C to 300C)

 

Flat Panel Display

QSi offers a series of optically clear silicones to help bond glass and plastics to flat panel and LCD displays.

Benefits of QSi’s Silicone Technology:

  • UV resistant
  • Non-yellowing catalyst systems are available
  • Pigmentable to provide contrast enhancement
  • Various bonding strengths from removable/repairable to permanent
  • Protects components from harsh environmental factors
  • Gel interlayer for glare reduction

 

Rollers

Liquid silicones from QSi have enhanced physical properties verses high consistency rubber and minimize manufacturing interruptions due to roller failure. QSi’s materials encompass copiers to large industrial manufacturing.

Benefits of QSi’s Silicone Technology:

  • Liquid silicone systems minimize defects in finished rollers
  • Low viscosity for ease in processing
  • Excellent machinability and grindability
  • Thermally conductive grades available
  • Low compression set
  • Wide selection of durometer specifications from 20 to 80 (Shore A) are available
  • Good chemical resistance
  • High operating temperature materials available up to 260C

 

LED Video Display

Potting and encapsulating products provide a protective barrier against moisture and environmental contaminants. QSi’s materials provide contrast enhancement that yields high resolution for your application. Materials range from optically clear to highly filled grades for thermal conductivity.

Benefits of QSi’s Silicone Technology:

  • Repairable
  • Environmental protection
  • UL listed grades are available (See our UL Rating File Number QMFZ2.E205830)
  • Encapsulants with high refractive indices are available to yield higher light outputs
  • Non-yellowing catalyst systems are available
  • Self-bonding grades available
  • Materials with low viscosity flow easily around complex parts and minimize air entrapment
  • Lower risk for delamination from CTE mismatch
  • Withstand extreme temperatures from -55C to 204C (Customized temperature ranges are available from -110C to 300C)
  • Thermally conductive grades are available

 

Dental

QM 1125 from QSi’s Moldmaking series is a leader in the dental duplication industry. Properties of QM 1125 benefit the silicone duplication process because of its ability to precisely replicate intricate details. It is fast curing, has a low viscosity (very flowable) and comes in a convenient 1:1 mix ratio. With a linear shrinkage at less than 0.1 percent, QM 1125’s fast demold time will also ensure a quick turn-around.
 

Food Contact

QSi has an extensive selection of moldmaking silicones that are ideal for indirect food contact. These products are compliant with FDA 21 CFR 177.2600 standard, and are flexible, reliable and cost effective.

Moldmaking How-To Guide: Steps in Creating a One Part Mold

Whether you are casting polyurethane foam, polyurethane resin, polyester, gypsum, stones, or low melt alloys like bronze, you can rely on QSi’s moldmaking silicones to consistently produce replicas. Below are seven steps in creating a one part mold. Click each image below to enlarge the photo. Please be sure to contact our sales or technical team to discuss your moldmaking application.

 

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 Download a PDF of this Moldmaking How-To Guide > >

Moldmaking How-To Guide: Steps in Creating a Two Part Mold

Whether you are casting polyurethane foam, polyurethane resin, polyester, gypsum, stones, or low melt alloys like bronze, you can rely on QSi’s moldmaking silicones to consistently produce replicas. Below are seven steps in creating a one part mold. Click each image below to enlarge the photo. Please be sure to contact our sales or technical team to discuss your moldmaking application.

 

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 Download a PDF of this Moldmaking How-To Guide > >

Identifying Chemicals that Cause Inhibition

There are many known chemicals to cause inhibition in addition curing silicones. Addition cure silicones use a platinum catalyst which reacts to effect the curing reaction when the “A” component is mixed with the “B” component. The platinum can become deactivated by coming in contact with certain chemical species. Once the catalyst is deactivated or poisoned, the affected area of silicone may never cure to the proper state of cure – meaning the inhibited area may stay runny, sticky, or fluid.

There are varying degrees of cure inhibition. The affected area could range from a complete non-cure to a slimy or sticky surface. The level of inhibition is determined by the type as well as the amount of the chemical species that the catalyzed silicone compound comes in contact with.

Here is a partial list of some of the more common materials that are known to cause cure inhibition. Please note, this is by no means a complete list of all problematic materials and is intended as a guide.

 

Compounds containing:

  • Amines and amides
  • Neutralizing amines
  • Ethanolamine, N-methylethanolamine, triethanolamine
  • N, N-dimethyl ethanolamine, n-butylamine, diethylamine
  • Triethylamine, tetramethylenediamine, cyclohexylamine
  • Melamine
  • Dimethylformamide
  • Nitriles, cyanates, oximo, nitroso, hydrazo, azo compounds
  • Adiponitrile
  • 2-butoxime
  • Alpha-nitroso-beta-naphthol
  • Chelates
  • EDTA (ethylenediaminetetraacetic acid)
  • NTA (nitriloacetic acid)

Compounds containing sulfur:

  • Sulfides, thio compounds
    1. Dibenzyldisulfide, thioacetic acid, allylthiourea

Compounds containing tin:

  • Fatty acid tin salts, such as those used in tin-catalyzed silicone release coatings

Compounds containing phosphorus:

  • Phosphines
    1. Triphenylphosphine
  • Phosphites
    1. Triethylphosphite

Compounds containing arsenic, antimony, selenium, tellurium:

  • Arsines, stibenes, selenide, telluride
    1. Triphenylarsine, triphenylstibene
    2. P-chlorophenylcarboxymethylselenide

Residual solvents or monomers:

  • Chlorinated hydrocarbons that contain amine stabilizers
  • Alcohols
    1. Ethanol, methanol
  • Esters
    1. Ethyl acetate, vinyl acetate
  • Compounds with unsaturated bonds

Primers that may inhibit cure:

  • Polyethylene that has an anti-slip, antioxidant or other additive listed previously
  • Primers with pigments that contain compounds listed previously
  • 100% sodium salt primers, such as sodium alginate or carboxymethylcellulose sodium salt; however, if these salts are used with hydroxyethylcellulose, inhibition will not occur
  • Clay coatings that use polyvinylacetate or acrylic latex as a binder
  • Coatings that contain calcium carbonate
  • Coatings composed of the following combinations:
    1. Natural rubber latex/clay; latex/ethylated starch
    2. Styrene/acrylic
    3. Polyvinylacetate; polyvinylacetate/acrylic

Filters

QSi has designed a variety of silicone gels for the filtration industry.  QSi’s silicone gels are used in the pharmaceutical, nuclear, industrial and automotive markets among others.

Benefits of QSi’s Silicone Technology:

  • Excellent resistance to certain cleaning chemicals, such as PAO and DOP
  • Moisture protection
  • Fast room temperature cures – reducing production times
  • Withstand extreme temperatures from -55C to 204C (Customized temperature ranges are available from -113C to 240C)
  • Technology available to minimize extractables
  • Thixotropic grades available

 

RTV Silicone Adhesive Sealants

Room temperature vulcanizing (RTV) silicone chemistry is the most widely used in formulating silicone adhesive sealants. This system utilizes moisture in the atmosphere to react with chemical crosslinkers, enabling the formation of a silicone elastomer. RTV silicones are normally described in terms of the small amount of the chemical by-product produced during the reaction.

The most common systems are:

  • Acetoxy
  • Oxime
  • Alkoxy or Methoxy
  • Acetone

All of these alternative cure mechanisms will lead to the formation of an elastic and relatively tough silicone rubber. However, some of the final physical properties of these rubbers will be substantially different.  The chemical by-products have an impact on the products suitability for certain applications and will also affect the way the adhesive can be handled from a heath and safety standpoint.

Each curing system has some advantages and disadvantages. Therefore, it is important to consider the materials being used, the operating environment and the production methods employed before you select your RTV silicone.  Acetone cure silicone adhesives have many technical advantages and are now being specified for a wide variety of applications especially within electronics.

RTV silicones are extremely flexible and user friendly.  Application can be made using handheld tubes and cartridge guns, or fully automated dispensing systems utilizing pails or drums.

View QSi’s series of One Component Silicone Adhesive Sealants

Health Care

Silicone gels by QSi are used to create cushioned external prosthetics, while tacky gels can function as an adhesive for the prosthetics. Because QSi’s silicone gels are very soft and retain their form once cured, they provide comfortable padding for hospital beds, wheelchair pillows, and sole cushioning in footwear.

 

Benefits of QSi’s Silicone Technology:

  • Pigmentable
  • Primerless adhesion
  • Soft, but resilient
  • Remains tacky even when exposed to moisture
  • Low viscosity for easy dispensing

 

 

Liquid silicone rubber inherently are non-irritant to skin. Prosthetic liners and other prostheses made of silicone will prove to be beneficial because of their versatile properties:

  • Comfortable against skin
  • Endure long-term wear and daily stretching
  • Can be molded to fit specific shapes and sizes
  • Can be designed to match unique skin features